From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Mon, 23 May 2011 13:39:19 +0100 Subject: [Cluster-devel] [PATCH 2/2] GFS2: Wait properly when flushing the ail list In-Reply-To: <1306154359-7046-1-git-send-email-swhiteho@redhat.com> References: <1306154359-7046-1-git-send-email-swhiteho@redhat.com> Message-ID: <1306154359-7046-3-git-send-email-swhiteho@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit The ail flush code has always relied upon log flushing to prevent it from spinning needlessly. This fixes it to wait on the last I/O request submitted (we don't need to wait for all of it) instead of either spinning with io_schedule or sleeping. As a result cpu usage of gfs2_logd is much reduced with certain workloads. Reported-by: Abhijith Das Tested-by: Abhijith Das Signed-off-by: Steven Whitehouse diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c index cec26c0..903115f 100644 --- a/fs/gfs2/log.c +++ b/fs/gfs2/log.c @@ -228,6 +228,27 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp) return ret; } +static void gfs2_ail1_wait(struct gfs2_sbd *sdp) +{ + struct gfs2_ail *ai; + struct gfs2_bufdata *bd; + struct buffer_head *bh; + + spin_lock(&sdp->sd_ail_lock); + list_for_each_entry_reverse(ai, &sdp->sd_ail1_list, ai_list) { + list_for_each_entry(bd, &ai->ai_ail1_list, bd_ail_st_list) { + bh = bd->bd_bh; + if (!buffer_locked(bh)) + continue; + get_bh(bh); + spin_unlock(&sdp->sd_ail_lock); + wait_on_buffer(bh); + brelse(bh); + return; + } + } + spin_unlock(&sdp->sd_ail_lock); +} /** * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced @@ -878,9 +899,9 @@ void gfs2_meta_syncfs(struct gfs2_sbd *sdp) gfs2_log_flush(sdp, NULL); for (;;) { gfs2_ail1_start(sdp); + gfs2_ail1_wait(sdp); if (gfs2_ail1_empty(sdp)) break; - msleep(10); } } @@ -920,12 +941,14 @@ int gfs2_logd(void *data) if (gfs2_ail_flush_reqd(sdp)) { gfs2_ail1_start(sdp); - io_schedule(); + gfs2_ail1_wait(sdp); gfs2_ail1_empty(sdp); gfs2_log_flush(sdp, NULL); } - wake_up(&sdp->sd_log_waitq); + if (!gfs2_ail_flush_reqd(sdp)) + wake_up(&sdp->sd_log_waitq); + t = gfs2_tune_get(sdp, gt_logd_secs) * HZ; if (freezing(current)) refrigerator(); -- 1.7.4