mirror_zfs/tests/zfs-tests/tests/functional/mmap
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
..
cleanup.ksh Add the ZFS Test Suite 2016-03-16 13:46:16 -07:00
Makefile.am Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2022-05-03 13:23:26 -07:00
mmap_libaio_001_pos.ksh tests: get rid of which 2022-04-01 17:57:25 -07:00
mmap_read_001_pos.ksh Fix typos 2020-06-09 21:24:09 -07:00
mmap_seek_001_pos.ksh Fix lseek(SEEK_DATA/SEEK_HOLE) mmap consistency 2021-11-07 14:27:44 -07:00
mmap_sync_001_pos.ksh Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2022-05-03 13:23:26 -07:00
mmap_write_001_pos.ksh Fix typos in tests/ 2019-09-02 18:10:31 -07:00
mmap.cfg Real disk partitioning now enabled in test suite for Linux 2016-09-08 13:45:34 -07:00
setup.ksh Add the ZFS Test Suite 2016-03-16 13:46:16 -07:00