On Thu, 2011-08-25 at 17:17 +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> The AIL push code will issue a log force on ever single push loop
> that it exits and has encountered pinned items. It doesn't rescan
> these pinned items until it revisits the AIL from the start. Hence
> we only need to force the log once per walk from the start of the
> AIL to the target LSN.
>
> This results in numbers like this:
>
> xs_push_ail_flush..... 1456
> xs_log_force......... 1485
>
> For an 8-way 50M inode create workload - almost all the log forces
> are coming from the AIL pushing code.
>
> Reduce the number of log forces by only forcing the log if the
> previous walk found pinned buffers. This reduces the numbers to:
>
> xs_push_ail_flush..... 665
> xs_log_force......... 682
>
> For the same test.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
This looks good to me and if you don't update it
I can take it as-is. A couple trivial things below
if you decide to update.
Reviewed-by: Alex Elder <aelder@xxxxxxx>
> ---
> fs/xfs/xfs_trans_ail.c | 28 ++++++++++++++++------------
> fs/xfs/xfs_trans_priv.h | 1 +
> 2 files changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
> index c15aa29..dd966e0 100644
> --- a/fs/xfs/xfs_trans_ail.c
> +++ b/fs/xfs/xfs_trans_ail.c
> @@ -372,12 +372,24 @@ xfs_ail_worker(
> xfs_lsn_t lsn;
> xfs_lsn_t target;
> long tout = 10;
> - int flush_log = 0;
> int stuck = 0;
> int count = 0;
> int push_xfsbufd = 0;
>
> + /*
> + * If last time we ran we encountered pinned items, force the log first,
> + * wait for it and then push again.
* and wait for it before we push it again.
*/
> + */
> spin_lock(&ailp->xa_lock);
> + if (ailp->xa_last_pushed_lsn == 0 && ailp->xa_log_flush &&
> + !list_empty(&ailp->xa_ail)) {
> + ailp->xa_log_flush = 0;
> + spin_unlock(&ailp->xa_lock);
> + XFS_STATS_INC(xs_push_ail_flush);
> + xfs_log_force(mp, XFS_LOG_SYNC);
> + spin_lock(&ailp->xa_lock);
> + }
This is a definite improvement over the previous version.
> +
> target = ailp->xa_target;
> lip = xfs_trans_ail_cursor_first(ailp, &cur, ailp->xa_last_pushed_lsn);
> if (!lip || XFS_FORCED_SHUTDOWN(mp)) {
> @@ -391,6 +403,7 @@ xfs_ail_worker(
>
> XFS_STATS_INC(xs_push_ail);
>
> +
> /*
> * While the item we are looking at is below the given threshold
> * try to flush it out. We'd like not to stop until we've at least
Kill this hunk.
. . .
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