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xfs: reduce context switches for synchronous buffered I/O

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Currently all metadata I/O completions happen in the m_buf_workqueue
workqueue.  But for synchronous I/O (i.e. all buffer reads) there is no
need for that, as there always is a called in process context that is
waiting for the I/O.  Factor out the guts of xfs_buf_ioend into a
separate helper and call it from xfs_buf_iowait to avoid a double
an extra context switch to the workqueue.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Christoph Hellwig 2025-02-24 15:48:52 -08:00 • committed by Carlos Maiolino
parent 2d873efd17
commit 4b90de5bc0
1 changed files with 27 additions and 16 deletions
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43
fs/xfs/xfs_buf.c
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@ -1345,6 +1345,7 @@ xfs_buf_ioend_handle_error(
resubmit:
xfs_buf_ioerror(bp, 0);
bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
reinit_completion(&bp->b_iowait);
xfs_buf_submit(bp);
return true;
out_stale:
@ -1355,8 +1356,9 @@ out_stale:
return false;
}
static void
xfs_buf_ioend(
/* returns false if the caller needs to resubmit the I/O, else true */
static bool
__xfs_buf_ioend(
struct xfs_buf *bp)
{
trace_xfs_buf_iodone(bp, _RET_IP_);
@ -1376,7 +1378,7 @@ xfs_buf_ioend(
}
if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
return;
return false;
/* clear the retry state */
bp->b_last_error = 0;
@ -1397,7 +1399,15 @@ xfs_buf_ioend(
bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
_XBF_LOGRECOVERY);
return true;
}
static void
xfs_buf_ioend(
struct xfs_buf *bp)
{
if (!__xfs_buf_ioend(bp))
return;
if (bp->b_flags & XBF_ASYNC)
xfs_buf_relse(bp);
else
@ -1411,15 +1421,8 @@ xfs_buf_ioend_work(
struct xfs_buf *bp =
container_of(work, struct xfs_buf, b_ioend_work);
xfs_buf_ioend(bp);
}
static void
xfs_buf_ioend_async(
struct xfs_buf *bp)
{
INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
if (__xfs_buf_ioend(bp))
xfs_buf_relse(bp);
}
void
@ -1491,7 +1494,13 @@ xfs_buf_bio_end_io(
XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
xfs_buf_ioerror(bp, -EIO);
xfs_buf_ioend_async(bp);
if (bp->b_flags & XBF_ASYNC) {
INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
} else {
complete(&bp->b_iowait);
}
bio_put(bio);
}
@ -1568,9 +1577,11 @@ xfs_buf_iowait(
{
ASSERT(!(bp->b_flags & XBF_ASYNC));
trace_xfs_buf_iowait(bp, _RET_IP_);
wait_for_completion(&bp->b_iowait);
trace_xfs_buf_iowait_done(bp, _RET_IP_);
do {
trace_xfs_buf_iowait(bp, _RET_IP_);
wait_for_completion(&bp->b_iowait);
trace_xfs_buf_iowait_done(bp, _RET_IP_);
} while (!__xfs_buf_ioend(bp));
return bp->b_error;
}