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| author | Dave Chinner <dchinner@redhat.com> | 2010-12-03 22:11:29 +1100 |
|---|---|---|
| committer | Dave Chinner <david@fromorbit.com> | 2010-12-03 22:11:29 +1100 |
| commit | 84f3c683c4d3f36d3c3ed320babd960a332ac458 (patch) | |
| tree | 5884f4e5a04a7a67c634e003bfa590fd2e643fdc /fs/xfs/xfs_log_priv.h | |
| parent | 2ced19cbae5448b720919a494606c62095d4f4db (diff) | |
| download | linux-stable-84f3c683c4d3f36d3c3ed320babd960a332ac458.tar.gz linux-stable-84f3c683c4d3f36d3c3ed320babd960a332ac458.tar.bz2 linux-stable-84f3c683c4d3f36d3c3ed320babd960a332ac458.zip | |
xfs: convert l_last_sync_lsn to an atomic variable
log->l_last_sync_lsn is updated in only one critical spot - log
buffer Io completion - and is protected by the grant lock here. This
requires the grant lock to be taken for every log buffer IO
completion. Converting the l_last_sync_lsn variable to an atomic64_t
means that we do not need to take the grant lock in log buffer IO
completion to update it.
This also removes the need for explicitly holding a spinlock to read
the l_last_sync_lsn on 32 bit platforms.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs/xfs_log_priv.h')
| -rw-r--r-- | fs/xfs/xfs_log_priv.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h index e2bb276eb2a7..958f356df10e 100644 --- a/fs/xfs/xfs_log_priv.h +++ b/fs/xfs/xfs_log_priv.h @@ -507,7 +507,6 @@ typedef struct log { spinlock_t l_icloglock; /* grab to change iclog state */ xfs_lsn_t l_tail_lsn; /* lsn of 1st LR with unflushed * buffers */ - xfs_lsn_t l_last_sync_lsn;/* lsn of last LR on disk */ int l_curr_cycle; /* Cycle number of log writes */ int l_prev_cycle; /* Cycle number before last * block increment */ @@ -521,6 +520,14 @@ typedef struct log { int64_t l_grant_reserve_head; int64_t l_grant_write_head; + /* + * l_last_sync_lsn is an atomic so it can be set and read without + * needing to hold specific locks. To avoid operations contending with + * other hot objects, place it on a separate cacheline. + */ + /* lsn of last LR on disk */ + atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp; + /* The following field are used for debugging; need to hold icloglock */ #ifdef DEBUG char *l_iclog_bak[XLOG_MAX_ICLOGS]; |