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GFS2: Wait properly when flushing the ail list

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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 <adas@redhat.com>
Tested-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
Steven Whitehouse 2011-05-21 19:21:07 +01:00
parent 6d3117b412
commit 26b06a6958
1 changed files with 26 additions and 3 deletions
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29
fs/gfs2/log.c
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@ -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();