mirror_zfs/module
Shaan Nobee 411f4a018d
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
2022-05-03 13:23:26 -07:00
..
avl linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
icp linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
lua linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
nvpair linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
os Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2022-05-03 13:23:26 -07:00
unicode linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
zcommon Improve zpool status output, list all affected datasets 2022-04-25 17:25:42 -07:00
zfs Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2022-05-03 13:23:26 -07:00
zstd Silence unused-but-set-variable warnings 2022-04-29 14:21:11 -07:00
.gitignore Cleanup linux module kbuild files 2020-06-10 09:24:15 -07:00
Kbuild.in linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
Makefile.bsd Fix ACL checks for NFS kernel server 2022-03-18 06:47:57 -06:00
Makefile.in linux: module: uninstall legacy modules on (un)installation 2022-04-20 13:28:54 -07:00