mirror_zfs/module
Shaan Nobee 9e5a297de6 Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously
Page writebacks with WB_SYNC_NONE can take several seconds to complete
since they wait for the transaction group to close before being
committed. This is usually not a problem since the caller does not
need to wait. However, if we're simultaneously doing a writeback
with WB_SYNC_ALL (e.g via msync), the latter can block for several
seconds (up to zfs_txg_timeout) due to the active WB_SYNC_NONE
writeback since it needs to wait for the transaction to complete
and the PG_writeback bit to be cleared.

This commit deals with 2 cases:

- No page writeback is active. A WB_SYNC_ALL page writeback starts
  and even completes. But when it's about to check if the PG_writeback
  bit has been cleared, another writeback with WB_SYNC_NONE starts.
  The sync page writeback ends up waiting for the non-sync page
  writeback to complete.

- A page writeback with WB_SYNC_NONE is already active when a
  WB_SYNC_ALL writeback starts. The WB_SYNC_ALL writeback ends up
  waiting for the WB_SYNC_NONE writeback.

The fix works by carefully keeping track of active sync/non-sync
writebacks and committing when beneficial.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Shaan Nobee <sniper111@gmail.com>
Closes #12662
Closes #12790
2023-06-05 10:59:02 -07:00
..
avl AVL: Remove obsolete branching optimizations 2022-07-26 10:10:37 -07:00
icp Fix possible NULL pointer dereference in sha2_mac_init() 2022-12-01 12:39:42 -08:00
lua Lua: Fix bad bitshift in lua_strx2number() 2022-12-01 12:39:44 -08:00
nvpair Update checkstyle workflow env to ubuntu-20.04 2021-12-08 13:27:56 -08:00
os Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2023-06-05 10:59:02 -07:00
spl Cleanup linux module kbuild files 2020-06-10 09:24:15 -07:00
unicode Illumos #15286: do_composition() needs sign awareness 2023-01-19 12:50:42 -08:00
zcommon dsl_prop_known_index(): check for invalid prop 2022-11-08 10:16:21 -08:00
zfs Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2023-06-05 10:59:02 -07:00
zstd module: zstd: check we don't leak symbols; regenerate symbol map 2022-05-16 15:48:21 -07:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-09-28 10:35:13 -07:00
Kbuild.in Add zstd support to zfs 2020-08-20 10:30:06 -07:00
Makefile.bsd FreeBSD: Silence clang unused-but-set-variable 2022-06-15 11:27:28 -07:00
Makefile.in Add support for $KERNEL_{CC,LD,LLVM} variables 2022-02-16 17:58:55 -08:00