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OpenZFS 6569 - large file delete can starve out write ops

Authored by: Alek Pinchuk <alek@nexenta.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Sanjay Nadkarni <sanjay.nadkarni@nexenta.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: George Melikov <mail@gmelikov.ru>
Tested-by: kernelOfTruth <kerneloftruth@gmail.com>

OpenZFS-issue: https://www.illumos.org/issues/6569
OpenZFS-commit: openzfs/openzfs@1bf4b6f
Closes #5706
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gmelikov authored and behlendorf committed Jan 31, 2017
1 parent a873815 commit 539d33c791da2f970cfa5a1bddf0533b23146265
Showing with 94 additions and 5 deletions.
  1. +2 −0 include/sys/dsl_pool.h
  2. +30 −0 include/sys/trace_dmu.h
  3. +51 −5 module/zfs/dmu.c
  4. +11 −0 module/zfs/dsl_pool.c
@@ -21,6 +21,7 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013 by Delphix. All rights reserved.
* Copyright 2016 Nexenta Systems, Inc. All rights reserved.
*/

#ifndef _SYS_DSL_POOL_H
@@ -106,6 +107,7 @@ typedef struct dsl_pool {
kcondvar_t dp_spaceavail_cv;
uint64_t dp_dirty_pertxg[TXG_SIZE];
uint64_t dp_dirty_total;
uint64_t dp_long_free_dirty_pertxg[TXG_SIZE];
uint64_t dp_mos_used_delta;
uint64_t dp_mos_compressed_delta;
uint64_t dp_mos_uncompressed_delta;
@@ -112,6 +112,36 @@ DEFINE_EVENT(zfs_delay_mintime_class, name, \
/* END CSTYLED */
DEFINE_DELAY_MINTIME_EVENT(zfs_delay__mintime);

/* BEGIN CSTYLED */
DECLARE_EVENT_CLASS(zfs_free_long_range_class,
TP_PROTO(uint64_t long_free_dirty_all_txgs, uint64_t chunk_len, \
uint64_t txg),
TP_ARGS(long_free_dirty_all_txgs, chunk_len, txg),
TP_STRUCT__entry(
__field(uint64_t, long_free_dirty_all_txgs)
__field(uint64_t, chunk_len)
__field(uint64_t, txg)
),
TP_fast_assign(
__entry->long_free_dirty_all_txgs = long_free_dirty_all_txgs;
__entry->chunk_len = chunk_len;
__entry->txg = txg;
),
TP_printk("long_free_dirty_all_txgs %llu chunk_len %llu txg %llu",
__entry->long_free_dirty_all_txgs,
__entry->chunk_len, __entry->txg)
);
/* END CSTYLED */

/* BEGIN CSTYLED */
#define DEFINE_FREE_LONG_RANGE_EVENT(name) \
DEFINE_EVENT(zfs_free_long_range_class, name, \
TP_PROTO(uint64_t long_free_dirty_all_txgs, \
uint64_t chunk_len, uint64_t txg), \
TP_ARGS(long_free_dirty_all_txgs, chunk_len, txg))
/* END CSTYLED */
DEFINE_FREE_LONG_RANGE_EVENT(zfs_free__long__range);

#endif /* _TRACE_DMU_H */

#undef TRACE_INCLUDE_PATH
@@ -48,6 +48,7 @@
#include <sys/sa.h>
#include <sys/zfeature.h>
#include <sys/abd.h>
#include <sys/trace_dmu.h>
#ifdef _KERNEL
#include <sys/vmsystm.h>
#include <sys/zfs_znode.h>
@@ -58,6 +59,14 @@
*/
int zfs_nopwrite_enabled = 1;

/*
* Tunable to control percentage of dirtied blocks from frees in one TXG.
* After this threshold is crossed, additional dirty blocks from frees
* wait until the next TXG.
* A value of zero will disable this throttle.
*/
uint32_t zfs_per_txg_dirty_frees_percent = 30;

const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES] = {
{ DMU_BSWAP_UINT8, TRUE, "unallocated" },
{ DMU_BSWAP_ZAP, TRUE, "object directory" },
@@ -727,6 +736,9 @@ dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
{
uint64_t object_size;
int err;
uint64_t dirty_frees_threshold;
dsl_pool_t *dp = dmu_objset_pool(os);
int t;

if (dn == NULL)
return (SET_ERROR(EINVAL));
@@ -735,11 +747,18 @@ dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
if (offset >= object_size)
return (0);

if (zfs_per_txg_dirty_frees_percent <= 100)
dirty_frees_threshold =
zfs_per_txg_dirty_frees_percent * zfs_dirty_data_max / 100;
else
dirty_frees_threshold = zfs_dirty_data_max / 4;

if (length == DMU_OBJECT_END || offset + length > object_size)
length = object_size - offset;

while (length != 0) {
uint64_t chunk_end, chunk_begin;
uint64_t chunk_end, chunk_begin, chunk_len;
uint64_t long_free_dirty_all_txgs = 0;
dmu_tx_t *tx;

if (dmu_objset_zfs_unmounting(dn->dn_objset))
@@ -754,9 +773,28 @@ dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
ASSERT3U(chunk_begin, >=, offset);
ASSERT3U(chunk_begin, <=, chunk_end);

chunk_len = chunk_end - chunk_begin;

mutex_enter(&dp->dp_lock);
for (t = 0; t < TXG_SIZE; t++) {
long_free_dirty_all_txgs +=
dp->dp_long_free_dirty_pertxg[t];
}
mutex_exit(&dp->dp_lock);

/*
* To avoid filling up a TXG with just frees wait for
* the next TXG to open before freeing more chunks if
* we have reached the threshold of frees
*/
if (dirty_frees_threshold != 0 &&
long_free_dirty_all_txgs >= dirty_frees_threshold) {
txg_wait_open(dp, 0);
continue;
}

tx = dmu_tx_create(os);
dmu_tx_hold_free(tx, dn->dn_object,
chunk_begin, chunk_end - chunk_begin);
dmu_tx_hold_free(tx, dn->dn_object, chunk_begin, chunk_len);

/*
* Mark this transaction as typically resulting in a net
@@ -768,10 +806,18 @@ dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset,
dmu_tx_abort(tx);
return (err);
}
dnode_free_range(dn, chunk_begin, chunk_end - chunk_begin, tx);

mutex_enter(&dp->dp_lock);
dp->dp_long_free_dirty_pertxg[dmu_tx_get_txg(tx) & TXG_MASK] +=
chunk_len;
mutex_exit(&dp->dp_lock);
DTRACE_PROBE3(free__long__range,
uint64_t, long_free_dirty_all_txgs, uint64_t, chunk_len,
uint64_t, dmu_tx_get_txg(tx));
dnode_free_range(dn, chunk_begin, chunk_len, tx);
dmu_tx_commit(tx);

length -= chunk_end - chunk_begin;
length -= chunk_len;
}
return (0);
}
@@ -23,6 +23,7 @@
* Copyright (c) 2011, 2015 by Delphix. All rights reserved.
* Copyright (c) 2013 Steven Hartland. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
* Copyright 2016 Nexenta Systems, Inc. All rights reserved.
*/

#include <sys/dsl_pool.h>
@@ -509,6 +510,16 @@ dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
*/
dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);

/*
* Update the long range free counter after
* we're done syncing user data
*/
mutex_enter(&dp->dp_lock);
ASSERT(spa_sync_pass(dp->dp_spa) == 1 ||
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] == 0);
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] = 0;
mutex_exit(&dp->dp_lock);

/*
* After the data blocks have been written (ensured by the zio_wait()
* above), update the user/group space accounting.

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