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RDS: Use page_remainder_alloc() for recv bufs

Instead of splitting up a page into RDS_FRAG_SIZE chunks
ourselves, ask rds_page_remainder_alloc() to do it. While it
is possible PAGE_SIZE > FRAG_SIZE, on x86en it isn't, so having
duplicate "carve up a page into buffers" code seems excessive.

The other modification this spawns is the use of a single
struct scatterlist in rds_page_frag instead of a bare page ptr.
This causes verbosity to increase in some places, and decrease
in others.

Finally, I decided to unify the lifetimes and alloc/free of
rds_page_frag and its page. This is a nice simplification in itself,
but will be extra-nice once we come to adding cmason's recycling
patch.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
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1 parent fc19de3 commit 0b088e003ccf316a76c51be5dec2d70b93be3be8 Andy Grover committed May 25, 2010
Showing with 29 additions and 73 deletions.
  1. +1 −6 net/rds/ib.h
  2. +27 −67 net/rds/ib_recv.c
  3. +1 −0 net/rds/page.c
View
@@ -28,13 +28,9 @@ extern struct list_head rds_ib_devices;
* try and minimize the amount of memory tied up both the device and
* socket receive queues.
*/
-/* page offset of the final full frag that fits in the page */
-#define RDS_PAGE_LAST_OFF (((PAGE_SIZE / RDS_FRAG_SIZE) - 1) * RDS_FRAG_SIZE)
struct rds_page_frag {
struct list_head f_item;
- struct page *f_page;
- unsigned long f_offset;
- dma_addr_t f_mapped;
+ struct scatterlist f_sg;
};
struct rds_ib_incoming {
@@ -107,7 +103,6 @@ struct rds_ib_connection {
struct rds_header *i_recv_hdrs;
u64 i_recv_hdrs_dma;
struct rds_ib_recv_work *i_recvs;
- struct rds_page_frag i_frag;
u64 i_ack_recv; /* last ACK received */
/* sending acks */
View
@@ -43,17 +43,11 @@ static struct kmem_cache *rds_ib_incoming_slab;
static struct kmem_cache *rds_ib_frag_slab;
static atomic_t rds_ib_allocation = ATOMIC_INIT(0);
-static void rds_ib_frag_drop_page(struct rds_page_frag *frag)
-{
- rdsdebug("frag %p page %p\n", frag, frag->f_page);
- __free_page(frag->f_page);
- frag->f_page = NULL;
-}
-
+/* Free frag and attached recv buffer f_sg */
static void rds_ib_frag_free(struct rds_page_frag *frag)
{
- rdsdebug("frag %p page %p\n", frag, frag->f_page);
- BUG_ON(frag->f_page);
+ rdsdebug("frag %p page %p\n", frag, sg_page(&frag->f_sg));
+ __free_page(sg_page(&frag->f_sg));
kmem_cache_free(rds_ib_frag_slab, frag);
}
@@ -71,12 +65,8 @@ static void rds_ib_recv_unmap_page(struct rds_ib_connection *ic,
{
struct rds_page_frag *frag = recv->r_frag;
- rdsdebug("recv %p frag %p page %p\n", recv, frag, frag->f_page);
- if (frag->f_mapped)
- ib_dma_unmap_page(ic->i_cm_id->device,
- frag->f_mapped,
- RDS_FRAG_SIZE, DMA_FROM_DEVICE);
- frag->f_mapped = 0;
+ rdsdebug("recv %p frag %p page %p\n", recv, frag, sg_page(&frag->f_sg));
+ ib_dma_unmap_sg(ic->i_cm_id->device, &frag->f_sg, 1, DMA_FROM_DEVICE);
}
void rds_ib_recv_init_ring(struct rds_ib_connection *ic)
@@ -116,8 +106,6 @@ static void rds_ib_recv_clear_one(struct rds_ib_connection *ic,
}
if (recv->r_frag) {
rds_ib_recv_unmap_page(ic, recv);
- if (recv->r_frag->f_page)
- rds_ib_frag_drop_page(recv->r_frag);
rds_ib_frag_free(recv->r_frag);
recv->r_frag = NULL;
}
@@ -129,16 +117,12 @@ void rds_ib_recv_clear_ring(struct rds_ib_connection *ic)
for (i = 0; i < ic->i_recv_ring.w_nr; i++)
rds_ib_recv_clear_one(ic, &ic->i_recvs[i]);
-
- if (ic->i_frag.f_page)
- rds_ib_frag_drop_page(&ic->i_frag);
}
static int rds_ib_recv_refill_one(struct rds_connection *conn,
struct rds_ib_recv_work *recv)
{
struct rds_ib_connection *ic = conn->c_transport_data;
- dma_addr_t dma_addr;
struct ib_sge *sge;
int ret = -ENOMEM;
@@ -161,50 +145,27 @@ static int rds_ib_recv_refill_one(struct rds_connection *conn,
if (!recv->r_frag)
goto out;
INIT_LIST_HEAD(&recv->r_frag->f_item);
- recv->r_frag->f_page = NULL;
- }
-
- if (!ic->i_frag.f_page) {
- ic->i_frag.f_page = alloc_page(GFP_NOWAIT);
- if (!ic->i_frag.f_page)
+ sg_init_table(&recv->r_frag->f_sg, 1);
+ ret = rds_page_remainder_alloc(&recv->r_frag->f_sg,
+ RDS_FRAG_SIZE, GFP_NOWAIT);
+ if (ret) {
+ kmem_cache_free(rds_ib_frag_slab, recv->r_frag);
+ recv->r_frag = NULL;
goto out;
- ic->i_frag.f_offset = 0;
+ }
}
- dma_addr = ib_dma_map_page(ic->i_cm_id->device,
- ic->i_frag.f_page,
- ic->i_frag.f_offset,
- RDS_FRAG_SIZE,
- DMA_FROM_DEVICE);
- if (ib_dma_mapping_error(ic->i_cm_id->device, dma_addr))
- goto out;
-
- /*
- * Once we get the RDS_PAGE_LAST_OFF frag then rds_ib_frag_unmap()
- * must be called on this recv. This happens as completions hit
- * in order or on connection shutdown.
- */
- recv->r_frag->f_page = ic->i_frag.f_page;
- recv->r_frag->f_offset = ic->i_frag.f_offset;
- recv->r_frag->f_mapped = dma_addr;
+ ret = ib_dma_map_sg(ic->i_cm_id->device, &recv->r_frag->f_sg,
+ 1, DMA_FROM_DEVICE);
+ WARN_ON(ret != 1);
sge = &recv->r_sge[0];
sge->addr = ic->i_recv_hdrs_dma + (recv - ic->i_recvs) * sizeof(struct rds_header);
sge->length = sizeof(struct rds_header);
sge = &recv->r_sge[1];
- sge->addr = dma_addr;
- sge->length = RDS_FRAG_SIZE;
-
- get_page(recv->r_frag->f_page);
-
- if (ic->i_frag.f_offset < RDS_PAGE_LAST_OFF) {
- ic->i_frag.f_offset += RDS_FRAG_SIZE;
- } else {
- put_page(ic->i_frag.f_page);
- ic->i_frag.f_page = NULL;
- ic->i_frag.f_offset = 0;
- }
+ sge->addr = sg_dma_address(&recv->r_frag->f_sg);
+ sge->length = sg_dma_len(&recv->r_frag->f_sg);
ret = 0;
out:
@@ -247,8 +208,8 @@ int rds_ib_recv_refill(struct rds_connection *conn, int prefill)
/* XXX when can this fail? */
ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
rdsdebug("recv %p ibinc %p page %p addr %lu ret %d\n", recv,
- recv->r_ibinc, recv->r_frag->f_page,
- (long) recv->r_frag->f_mapped, ret);
+ recv->r_ibinc, sg_page(&recv->r_frag->f_sg),
+ (long) sg_dma_address(&recv->r_frag->f_sg), ret);
if (ret) {
rds_ib_conn_error(conn, "recv post on "
"%pI4 returned %d, disconnecting and "
@@ -281,7 +242,6 @@ static void rds_ib_inc_purge(struct rds_incoming *inc)
list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) {
list_del_init(&frag->f_item);
- rds_ib_frag_drop_page(frag);
rds_ib_frag_free(frag);
}
}
@@ -333,13 +293,13 @@ int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
to_copy = min_t(unsigned long, to_copy, len - copied);
rdsdebug("%lu bytes to user [%p, %zu] + %lu from frag "
- "[%p, %lu] + %lu\n",
+ "[%p, %u] + %lu\n",
to_copy, iov->iov_base, iov->iov_len, iov_off,
- frag->f_page, frag->f_offset, frag_off);
+ sg_page(&frag->f_sg), frag->f_sg.offset, frag_off);
/* XXX needs + offset for multiple recvs per page */
- ret = rds_page_copy_to_user(frag->f_page,
- frag->f_offset + frag_off,
+ ret = rds_page_copy_to_user(sg_page(&frag->f_sg),
+ frag->f_sg.offset + frag_off,
iov->iov_base + iov_off,
to_copy);
if (ret) {
@@ -595,7 +555,7 @@ static void rds_ib_cong_recv(struct rds_connection *conn,
to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
BUG_ON(to_copy & 7); /* Must be 64bit aligned. */
- addr = kmap_atomic(frag->f_page, KM_SOFTIRQ0);
+ addr = kmap_atomic(sg_page(&frag->f_sg), KM_SOFTIRQ0);
src = addr + frag_off;
dst = (void *)map->m_page_addrs[map_page] + map_off;
@@ -698,12 +658,12 @@ static void rds_ib_process_recv(struct rds_connection *conn,
* the inc is freed. We don't go that route, so we have to drop the
* page ref ourselves. We can't just leave the page on the recv
* because that confuses the dma mapping of pages and each recv's use
- * of a partial page. We can leave the frag, though, it will be
- * reused.
+ * of a partial page.
*
* FIXME: Fold this into the code path below.
*/
- rds_ib_frag_drop_page(recv->r_frag);
+ rds_ib_frag_free(recv->r_frag);
+ recv->r_frag = NULL;
return;
}
View
@@ -186,6 +186,7 @@ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
ret ? 0 : scat->length);
return ret;
}
+EXPORT_SYMBOL_GPL(rds_page_remainder_alloc);
static int rds_page_remainder_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)

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