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Better performance with O_DIRECT on zvols #12483
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I did three different flamegraph runs and saw roughly the same results. Here's one of the runs: (Note: for some reason these SVGs aren't interactive when I click on the links, but if I download them and run One thing that stood out was |
Not sure if this helps, but below are some of
|
I think I know what's going on here. TL;DR O_DIRECT bypasses the kernel page cache, giving better performance on zvols. Use O_DIRECT in your application or use the Long answer:
When I ran the same tests with O_DIRECT, I would see Just to be sure it wasn't ZFS behavior, I also explicitly cleared O_DIRECT on any zvol write: diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 8229bc9..e3c2e44 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -260,6 +260,9 @@ zfs_read(struct znode *zp, zfs_uio_t *uio, int ioflag, cred_t *cr)
while (n > 0) {
ssize_t nbytes = MIN(n, zfs_vnops_read_chunk_size -
P2PHASE(zfs_uio_offset(uio), zfs_vnops_read_chunk_size));
+
+ ioflag = ioflag & ~O_DIRECT;
+
#ifdef UIO_NOCOPY
if (zfs_uio_segflg(uio) == UIO_NOCOPY)
error = mappedread_sf(zp, nbytes, uio); ... but got the same performance results I saw earlier. Note that ZFS will always use the ARC in both the non-O_DIRECT and O_DIRECT cases (although this may change with #10018). Mounting zfs with Closing issue. |
I had an interesting conversation with @behlendorf about this issue. He thought that non-O_DIRECT case might be submitting tons of tiny, one-page, BIO requests to the zvol, wheras the O_DIRECT case would pass the larger, uncached, BIO directly. He further explained that the ZFS module takes all BIOs and sticks them on a single task queue, where they are then processed by a pool of worker threads. He speculated that the single task queue may be getting overwhelmed. I re-ran my earlier tests and confirmed this was a case. My test created 10 volumes, and then did parallel I thought I could just switch out the IO scheduler to aggregate the BIOs, but no other schedulers were listed as options for the zvol: $ cat /sys/class/block/zd0/queue/scheduler
none ... contrast that to: $ cat /sys/class/block/sda/queue/scheduler
noop [deadline] cfq I'm looking into ways to make this more efficient. |
That might be on me - in earlier attempts to fix the ZVOL issue, i had it set NOMERGES: commit 5731140eaf4aaf2526a8bfdbfe250195842e79eb
Author: RageLtMan <rageltman [at] sempervictus>
Date: Sat Mar 18 00:51:36 2017 -0400
Disable write merging on ZVOLs
The current ZVOL implementation does not explicitly set merge
options on ZVOL device queues, which results in the default merge
behavior.
Explicitly set QUEUE_FLAG_NOMERGES on ZVOL queues allowing the
ZIO pipeline to do its work.
Initial benchmarks (tiotest with no O_DIRECT) show random write
performance going up almost 3X on 8K ZVOLs, even after significant
rewrites of the logical space allocation.
Reviewed-by: Richard Yao <ryao@gentoo.org>
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: RageLtMan <rageltman@sempervictus>
Issue #5902
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index 7590ed3160..d0f7b9912b 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -1468,6 +1468,9 @@ zvol_alloc(dev_t dev, const char *name)
blk_queue_make_request(zv->zv_queue, zvol_request);
blk_queue_set_write_cache(zv->zv_queue, B_TRUE, B_TRUE);
+ /* Disable write merging in favor of the ZIO pipeline. */
+ queue_flag_set(QUEUE_FLAG_NOMERGES, zv->zv_queue);
+
zv->zv_disk = alloc_disk(ZVOL_MINORS);
if (zv->zv_disk == NULL)
goto out_queue; |
Doesn't BTRFS produce a volume type of some sort? How are they handling all of this? |
@sempervictus yea I tried commenting out those lines, but performance was unchanged 😞 I don't know if btrfs does volumes or not. |
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
All - I've opened a PR that improves zvol performance by using the kernel's blk-mq interface: #12664 However, there's still a lot of performance left on the table. The issue is that with O_DIRECT, the kernel gives you a
In the non-O_DIRECT case, it gives you a request with lots of little individual BIOs:
The zvol driver really wants big BIOs. Each BIO has to do a There are a couple of ways to fix this. One way is to treat the BIOs in the request as a group rather than processing them individually. That way we would only have to acquire one lock for a group of contiguous small BIOs (probably at a higher level of the zvol stack). The other option is to try to make a new Frankenstein BIO that merges all the smaller BIOs. I'm planning on looking into this further and coming up with a fix once #12664 is merged. I'm also changing the tile of this issue since the problem isn't dRAID specific. |
In the past ZVOLs exposed all available IO schedulers, but with a successive code refactoring only For a similar discussion, you can read here. In short:
Many users missed the old behavior, I should say. |
@shodanshok my blk-mq PR #12664 actually returns the |
@tonyhutter - IIRC, there was write-merging code prior to the gutting during 0.6(.4?). If we have Linux scheduling back, does that mean we have Linux write-merging back, and then does that also mean we're doing redundant work on the Linux-half and the DMU/ZIO pipeline-half again (de-duplication of which was at least part of the intent of said gutting)? |
@sempervictus when it comes to "write-merging", the devil is in the details. Under blk-mq, the kernel will "write-merge" multiple BIOs into one It's possible that on earlier, zfs-0.6.x-era kernels, the kernel merged BIOs into bigger BIOs, but I don't know if that's actually true or not. |
@tonyhutter: thanks for the clarification. It sounds like the dbuf hash locking bit is part of the problem with ZVOLs getting slower over time, so if we could have that change in this scope, it might help push out an otherwise ancient and evil problem with "filled" ZVOLs. |
@sempervictus yea, I plan to look into the dbuf hash locking as a follow-on PR once I get this and some other PRs checked in. |
Thank you sir, looking forward to it. |
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Signed-off-by: Tony Hutter <hutter2@llnl.gov> Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
Add support for the kernel's block multiqueue (blk-mq) interface in the zvol block driver. blk-mq creates multiple request queues on different CPUs rather than having a single request queue. This can improve zvol performance with multithreaded reads/writes. This implementation uses the blk-mq interfaces on 4.13 or newer kernels. Building against older kernels will fall back to the older BIO interfaces. Note that you must set the `zvol_use_blk_mq` module param to enable the blk-mq API. It is disabled by default. In addition, this commit lets the zvol blk-mq layer process whole `struct request` IOs at a time, rather than breaking them down into their individual BIOs. This reduces dbuf lock contention and overhead versus the legacy zvol submit_bio() codepath. sequential dd to one zvol, 8k volblocksize, no O_DIRECT: legacy submit_bio() 292MB/s write 453MB/s read this commit 453MB/s write 885MB/s read It also introduces a new `zvol_blk_mq_chunks_per_thread` module parameter. This parameter represents how many volblocksize'd chunks to process per each zvol thread. It can be used to tune your zvols for better read vs write performance (higher values favor write, lower favor read). Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com> Signed-off-by: Tony Hutter <hutter2@llnl.gov> Closes openzfs#13148 Issue openzfs#12483
System information
Describe the problem you're observing
One of our users was testing zvols on DRAID with a large number of disks, and reported much better performance when using O_DIRECT than without it (using multiple parallel
dd
writes). That seemed like an odd result, but my tests confirmed that as well. I was seeing around 1.7GByte/s vs 2.9GByte/s with O_DIRECT (on a 46-disk draid2:8d:46c:0s-0 pool, 12GBit SAS enclosure).The user reported seeing possible lock contention in the non-O_DIRECT case:
Describe how to reproduce the problem
Please adjust to your setup:
Include any warning/errors/backtraces from the system logs
Results:
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