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authorDave Chinner <dchinner@redhat.com>2020-03-25 06:10:29 +0300
committerDarrick J. Wong <darrick.wong@oracle.com>2020-03-27 18:32:55 +0300
commit8eb807bd839938b45bf7a97f0568d2a845ba6929 (patch)
tree31c41e5a41ed1953344bdd5038f8f7cae811788b /fs/xfs/xfs_inode_item.c
parent4165994ac9672d91134675caa6de3645a9ace6c8 (diff)
downloadlinux-8eb807bd839938b45bf7a97f0568d2a845ba6929.tar.xz
xfs: tail updates only need to occur when LSN changes
We currently wake anything waiting on the log tail to move whenever the log item at the tail of the log is removed. Historically this was fine behaviour because there were very few items at any given LSN. But with delayed logging, there may be thousands of items at any given LSN, and we can't move the tail until they are all gone. Hence if we are removing them in near tail-first order, we might be waking up processes waiting on the tail LSN to change (e.g. log space waiters) repeatedly without them being able to make progress. This also occurs with the new sync push waiters, and can result in thousands of spurious wakeups every second when under heavy direct reclaim pressure. To fix this, check that the tail LSN has actually changed on the AIL before triggering wakeups. This will reduce the number of spurious wakeups when doing bulk AIL removal and make this code much more efficient. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Allison Collins <allison.henderson@oracle.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_inode_item.c')
-rw-r--r--fs/xfs/xfs_inode_item.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index bd8c36809870..a627cb951dc6 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -730,19 +730,27 @@ xfs_iflush_done(
* holding the lock before removing the inode from the AIL.
*/
if (need_ail) {
- bool mlip_changed = false;
+ xfs_lsn_t tail_lsn = 0;
/* this is an opencoded batch version of xfs_trans_ail_delete */
spin_lock(&ailp->ail_lock);
list_for_each_entry(blip, &tmp, li_bio_list) {
if (INODE_ITEM(blip)->ili_logged &&
- blip->li_lsn == INODE_ITEM(blip)->ili_flush_lsn)
- mlip_changed |= xfs_ail_delete_one(ailp, blip);
- else {
+ blip->li_lsn == INODE_ITEM(blip)->ili_flush_lsn) {
+ /*
+ * xfs_ail_update_finish() only cares about the
+ * lsn of the first tail item removed, any
+ * others will be at the same or higher lsn so
+ * we just ignore them.
+ */
+ xfs_lsn_t lsn = xfs_ail_delete_one(ailp, blip);
+ if (!tail_lsn && lsn)
+ tail_lsn = lsn;
+ } else {
xfs_clear_li_failed(blip);
}
}
- xfs_ail_update_finish(ailp, mlip_changed);
+ xfs_ail_update_finish(ailp, tail_lsn);
}
/*