On Thu, Dec 12, 2013 at 09:25:07PM +1100, Dave Chinner wrote:
>
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Now that we have an atomic variable for the reference count, we
> don't need to take the dquot lock if we are not removing the last
> reference count. The dquot lock is a mutex, so we can't use
> atomic_dec_and_lock(), but we can open code it in xfs_qm_dqrele and
> hence avoid the dquot lock for most of the cases where we drop a
> reference count.
>
> The result is that concurrent file creates jump from 24,000/s to
> 28,000/s, and the entire workload is now serialised on the dquot
> being locked during transaction commit. Another significant win,
> even though it's not the big one...
Maybe I'm missing something, but shou;dn't the following be enough to
be a valid dqput (plus asserts & tracing):
if (atomic_dec_and_test(&dqp->q_nrefs)) {
if (list_lru_add(&mp->m_quotainfo->qi_lru, &dqp->q_lru))
XFS_STATS_INC(xs_qm_dquot_unused);
}
given that the only locking we need is the internal lru lock?
>
> While there, rename xfs_qm_dqrele to xfs_dqrele - the "qm" part of
> the name means nothing and just makes the code harder to read.
Please keep that out of the patch. I don't mind dropping the
qm_ part, but there's a lot of functions that have it, and it should
be done for all of them at the same time.
_______________________________________________
xfs mailing list
xfs@xxxxxxxxxxx
http://oss.sgi.com/mailman/listinfo/xfs
