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| author | Dave Chinner <dchinner@redhat.com> | 2020-05-20 23:17:11 +0300 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2020-05-27 18:49:25 +0300 |
| commit | b41b46c20c0bd32cd0a3795fcd2b892213cb6f5e (patch) | |
| tree | 3fb7d13542f6618934f0a022d14fc1864689268f /fs/xfs/xfs_mount.h | |
| parent | b0dff466c00975a3e3ec97e6b0266bfd3e4805d6 (diff) | |
| download | linux-b41b46c20c0bd32cd0a3795fcd2b892213cb6f5e.tar.xz | |
xfs: remove the m_active_trans counter
It's a global atomic counter, and we are hitting it at a rate of
half a million transactions a second, so it's bouncing the counter
cacheline all over the place on large machines. We don't actually
need it anymore - it used to be required because the VFS freeze code
could not track/prevent filesystem transactions that were running,
but that problem no longer exists.
Hence to remove the counter, we simply have to ensure that nothing
calls xfs_sync_sb() while we are trying to quiesce the filesytem.
That only happens if the log worker is still running when we call
xfs_quiesce_attr(). The log worker is cancelled at the end of
xfs_quiesce_attr() by calling xfs_log_quiesce(), so just call it
early here and then we can remove the counter altogether.
Concurrent create, 50 million inodes, identical 16p/16GB virtual
machines on different physical hosts. Machine A has twice the CPU
cores per socket of machine B:
unpatched patched
machine A: 3m16s 2m00s
machine B: 4m04s 4m05s
Create rates:
unpatched patched
machine A: 282k+/-31k 468k+/-21k
machine B: 231k+/-8k 233k+/-11k
Concurrent rm of same 50 million inodes:
unpatched patched
machine A: 6m42s 2m33s
machine B: 4m47s 4m47s
The transaction rate on the fast machine went from just under
300k/sec to 700k/sec, which indicates just how much of a bottleneck
this atomic counter was.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs/xfs_mount.h')
| -rw-r--r-- | fs/xfs/xfs_mount.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h index c1f92c1847bb..3725d25ad97e 100644 --- a/fs/xfs/xfs_mount.h +++ b/fs/xfs/xfs_mount.h @@ -176,7 +176,6 @@ typedef struct xfs_mount { uint64_t m_resblks; /* total reserved blocks */ uint64_t m_resblks_avail;/* available reserved blocks */ uint64_t m_resblks_save; /* reserved blks @ remount,ro */ - atomic_t m_active_trans; /* number trans frozen */ struct delayed_work m_reclaim_work; /* background inode reclaim */ struct delayed_work m_eofblocks_work; /* background eof blocks trimming */ |