mirror_zfs/module/zfs
Richard Yao bc17f1047a Enable Linux read-ahead for a single page on ZVOLs
Linux has read-ahead logic designed to accelerate sequential workloads.
ZFS has its own read-ahead logic called zprefetch that operates on both
ZVOLs and datasets. Having two prefetchers active at the same time can
cause overprefetching, which unnecessarily reduces IOPS performance on
CoW filesystems like ZFS.

Testing shows that entirely disabling the Linux prefetch results in
a significant performance penalty for reads while commensurate benefits
are seen in random writes. It appears that read-ahead benefits are
inversely proportional to random write benefits, and so a single page
of Linux-layer read-ahead appears to offer the middle ground for both
workloads.

Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Issue #5902
2017-05-04 18:00:27 -04:00
..
abd.c minor improvement to abd_free_pages() 2017-05-02 10:06:18 -07:00
arc.c Allow scaling of arc in proportion to pagecache 2017-05-02 15:50:49 -04:00
blkptr.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
bplist.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
bpobj.c panic in bpobj_space(): null pointer dereference 2017-02-09 10:19:12 -08:00
bptree.c OpenZFS 7082 - bptree_iterate() passes wrong args to zfs_dbgmsg() 2017-01-17 14:49:24 -08:00
bqueue.c Fix coverity defects: CID 147565-147567 2016-10-07 13:19:43 -07:00
dbuf_stats.c OpenZFS 6950 - ARC should cache compressed data 2016-09-13 09:58:33 -07:00
dbuf.c OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
ddt_zap.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
ddt.c Cache ddt_get_dedup_dspace() value if there was no ddt changes 2016-12-02 16:59:35 -07:00
dmu_diff.c OpenZFS 6950 - ARC should cache compressed data 2016-09-13 09:58:33 -07:00
dmu_object.c Clean up by-dnode code in dmu_tx.c 2017-02-24 13:34:26 -08:00
dmu_objset.c OpenZFS 7968 - multi-threaded spa_sync() 2017-03-20 18:36:00 -07:00
dmu_send.c OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
dmu_traverse.c Add TASKQID_INVALID 2016-11-02 12:14:45 -07:00
dmu_tx.c OpenZFS 7801 - add more by-dnode routines (lint) 2017-03-20 12:33:17 -07:00
dmu_zfetch.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
dmu.c OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
dnode_sync.c OpenZFS 7968 - multi-threaded spa_sync() 2017-03-20 18:36:00 -07:00
dnode.c OpenZFS 7968 - multi-threaded spa_sync() 2017-03-20 18:36:00 -07:00
dsl_bookmark.c OpenZFS 1300 - filename normalization doesn't work for removes 2017-02-02 14:13:41 -08:00
dsl_dataset.c OpenZFS 7968 - multi-threaded spa_sync() 2017-03-20 18:36:00 -07:00
dsl_deadlist.c panic in bpobj_space(): null pointer dereference 2017-02-09 10:19:12 -08:00
dsl_deleg.c Performance optimization of AVL tree comparator functions 2016-08-31 14:35:34 -07:00
dsl_destroy.c OpenZFS 7254 - ztest failed assertion in ztest_dataset_dirobj_verify: dirobjs + 1 == usedobjs 2017-01-27 11:43:42 -08:00
dsl_dir.c OpenZFS 7793 - ztest fails assertion in dmu_tx_willuse_space 2017-03-07 09:51:59 -08:00
dsl_pool.c OpenZFS 8026 - retire zfs_throttle_delay and zfs_throttle_resolution 2017-04-14 11:11:20 -07:00
dsl_prop.c Fix dsl_props_set_sync_impl to work with nested nvlist 2016-12-20 18:46:59 -08:00
dsl_scan.c OpenZFS 7254 - ztest failed assertion in ztest_dataset_dirobj_verify: dirobjs + 1 == usedobjs 2017-01-27 11:43:42 -08:00
dsl_synctask.c Illumos 4951 - ZFS administrative commands should use reserved space 2015-05-04 09:41:10 -07:00
dsl_userhold.c OpenZFS 6314 - buffer overflow in dsl_dataset_name 2016-06-28 13:47:03 -07:00
edonr_zfs.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
fm.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
gzip.c GZIP compression offloading with QAT accelerator 2017-03-22 17:58:47 -07:00
lz4.c OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
lzjb.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
Makefile.in GZIP compression offloading with QAT accelerator 2017-03-22 17:58:47 -07:00
metaslab.c OpenZFS 8023 - Panic destroying a metaslab deferred range tree 2017-04-09 16:12:35 -07:00
multilist.c OpenZFS 7968 - multi-threaded spa_sync() 2017-03-20 18:36:00 -07:00
pathname.c Add pn_alloc()/pn_free() functions 2016-04-21 09:49:25 -07:00
policy.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
qat_compress.c Change U16 to U32 due to atomic_inc_32_nv 2017-04-25 17:41:58 -07:00
qat_compress.h GZIP compression offloading with QAT accelerator 2017-03-22 17:58:47 -07:00
range_tree.c Performance optimization of AVL tree comparator functions 2016-08-31 14:35:34 -07:00
refcount.c Linux 4.11 compat: avoid refcount_t name conflict 2017-02-28 16:10:18 -08:00
rrwlock.c Fix spelling 2017-01-03 11:31:18 -06:00
sa.c OpenZFS 8061 - sa_find_idx_tab can be declared more type-safely 2017-04-14 11:11:28 -07:00
sha256.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
skein_zfs.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
spa_boot.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
spa_config.c Fix spelling 2017-01-03 11:31:18 -06:00
spa_errlog.c Illumos 4914 - zfs on-disk bookmark structure should be named *_phys_t 2014-08-06 14:48:41 -07:00
spa_history.c Fix indefinite article 2016-08-11 11:23:49 -07:00
spa_misc.c Fix size inflation in spa_get_worst_case_asize() 2017-04-10 15:28:21 -07:00
spa_stats.c Fix spelling 2017-01-03 11:31:18 -06:00
spa.c OpenZFS 5120 - zfs should allow large block/gzip/raidz boot pool (loader project) 2017-04-13 09:40:00 -07:00
space_map.c OpenZFS 8023 - Panic destroying a metaslab deferred range tree 2017-04-09 16:12:35 -07:00
space_reftree.c OpenZFS 6328 - Fix cstyle errors in zfs codebase 2017-01-12 09:42:11 -08:00
trace.c OpenZFS 6531 - Provide mechanism to artificially limit disk performance 2016-05-26 10:11:51 -07:00
txg.c Refactor txg history kstat 2016-12-02 16:57:49 -07:00
uberblock.c Illumos 5347 - idle pool may run itself out of space 2015-07-14 10:35:21 -07:00
unique.c Performance optimization of AVL tree comparator functions 2016-08-31 14:35:34 -07:00
vdev_cache.c Fix wrong offset args in vdev_cache_write 2017-03-28 11:06:22 -07:00
vdev_disk.c OpenZFS 7448 - ZFS doesn't notice when disk vdevs have no write cache 2017-02-04 09:23:50 -08:00
vdev_file.c Use a dedicated taskq for vdev_file 2016-12-21 10:47:15 -08:00
vdev_label.c Write label 2,3 uberblocks when vdev expands 2017-05-02 13:55:24 -07:00
vdev_mirror.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_missing.c Illumos #5244 - zio pipeline callers should explicitly invoke next stage 2015-04-30 15:07:47 -07:00
vdev_queue.c Increase zfs_vdev_async_write_min_active to 2 2017-04-14 14:03:44 -07:00
vdev_raidz_math_aarch64_neon_common.h ABD raidz NEON support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_aarch64_neon.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math_aarch64_neonx2.c ABD raidz NEON support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_avx2.c ABD raidz avx512f support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_avx512bw.c ABD: Adapt avx512bw raidz assembly 2016-12-15 17:31:33 -08:00
vdev_raidz_math_avx512f.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
vdev_raidz_math_impl.h codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math_scalar.c ABD Vectorized raidz 2016-11-29 14:34:33 -08:00
vdev_raidz_math_sse2.c ABD raidz avx512f support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_ssse3.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz.c Remove dependency on linear ABD 2017-03-29 12:24:51 -07:00
vdev_root.c Illumos #3598 2013-10-31 14:58:04 -07:00
vdev.c Write label 2,3 uberblocks when vdev expands 2017-05-02 13:55:24 -07:00
zap_leaf.c OpenZFS 1300 - filename normalization doesn't work for removes 2017-02-02 14:13:41 -08:00
zap_micro.c OpenZFS 7793 - ztest fails assertion in dmu_tx_willuse_space 2017-03-07 09:51:59 -08:00
zap.c OpenZFS 7793 - ztest fails assertion in dmu_tx_willuse_space 2017-03-07 09:51:59 -08:00
zfeature_common.c OpenZFS 2932 - support crash dumps to raidz, etc. pools 2017-04-10 10:24:17 -07:00
zfeature.c OpenZFS 6328 - Fix cstyle errors in zfs codebase 2017-01-12 09:42:11 -08:00
zfs_acl.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_byteswap.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
zfs_ctldir.c Restructure mount option handling 2017-03-10 09:51:41 -08:00
zfs_debug.c OpenZFS 7503 - zfs-test should tail ::zfs_dbgmsg on test failure 2017-04-12 13:36:48 -07:00
zfs_dir.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_fm.c Skip rate limiting events in zfs_ereport_post 2017-04-11 18:37:45 -07:00
zfs_fuid.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_ioctl.c OpenZFS 6101 - attempt to lzc_create() a filesystem under a volume results in a panic 2017-04-14 11:11:28 -07:00
zfs_log.c OpenZFS 6328 - Fix cstyle errors in zfs codebase 2017-01-12 09:42:11 -08:00
zfs_onexit.c zfsdev_getminor() should check for invalid file handles 2015-06-22 17:02:13 -07:00
zfs_replay.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_rlock.c Fix spelling 2017-01-03 11:31:18 -06:00
zfs_sa.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_vfsops.c Linux 4.12 compat: super_setup_bdi_name() 2017-05-02 09:46:18 -07:00
zfs_vnops.c Fix lseek result when dnode is dirty 2017-04-24 09:38:31 -07:00
zfs_znode.c Retry zfs_znode_alloc() in zfs_mknode() 2017-03-23 18:26:50 -07:00
zil.c OpenZFS 3821 - Race in rollback, zil close, and zil flush 2017-03-23 18:20:58 -07:00
zio_checksum.c Remove dependency on linear ABD 2017-03-29 12:24:51 -07:00
zio_compress.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
zio_inject.c Compile zio.h and zio_impl.h mutual include 2016-12-01 16:36:25 -07:00
zio.c Guarantee PAGESIZE alignment for large zio buffers 2017-05-02 10:04:30 -07:00
zle.c Update core ZFS code from build 121 to build 141. 2010-05-28 13:45:14 -07:00
zpl_ctldir.c Linux 4.11 compat: iops.getattr and friends 2017-03-20 17:51:16 -07:00
zpl_export.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
zpl_file.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zpl_inode.c Linux 4.11 compat: iops.getattr and friends 2017-03-20 17:51:16 -07:00
zpl_super.c Restructure mount option handling 2017-03-10 09:51:41 -08:00
zpl_xattr.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zrlock.c OpenZFS 3746 - ZRLs are racy 2017-01-23 10:35:58 -08:00
zvol.c Enable Linux read-ahead for a single page on ZVOLs 2017-05-04 18:00:27 -04:00