svn commit: r254846 - projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs

[Alexander Motin]

On 25.08.2013 15:48, Adrian Chadd wrote:
> Surely there's a better way to check whether a thread can sleep besides
> digging around in curthread->td_no_sleeping ? What about adding an
> accessor macro along side THREAD_SLEEPING_OK and THREAD_NO_SLEEPING ?

That sounds good to me. I was also surprised such macros are not there 
yet when found some code doing these checks just the same way as I did.

> I assume that td_no_sleeping won't change during the execution of a
> thread? (Eg if it's preempted by anything?) It looks like it's only set
> when doing rmlock, timeout or ithread calls, to ensure the thread
> doesn't sleep.

If that status will change somehow after the check, then it is problem 
of that specific code, not mine. Preemption should not affect it in any 
way since it is property of the specific thread.

> On 25 August 2013 04:21, Alexander Motin <mav at freebsd.org
> <mailto:mav at freebsd.org>> wrote:
>
>     Author: mav
>     Date: Sun Aug 25 11:21:10 2013
>     New Revision: 254846
>     URL: http://svnweb.freebsd.org/changeset/base/254846
>
>     Log:
>        Allow GEOM direct dispatch for zvol providers.  Skip request
>     handover to
>        the worker thread if current context allows sleeping (thanks to
>     the direct
>        dispatch in action we are not in GEOM thread).
>
>        Together this doubles zvol performance, reaching up to 300K IOPS
>     on my tests.
>        If there would be unmapped I/O support for zvols, the above value
>     could be
>        even bigger.
>
>     Modified:
>
>     projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>
>     Modified:
>     projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>     ==============================================================================
>     ---
>     projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>           Sun Aug 25 11:21:03 2013        (r254845)
>     +++
>     projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
>           Sun Aug 25 11:21:10 2013        (r254846)
>     @@ -2068,6 +2068,7 @@ zvol_geom_create(const char *name)
>              gp->start = zvol_geom_start;
>              gp->access = zvol_geom_access;
>              pp = g_new_providerf(gp, "%s/%s", ZVOL_DRIVER, name);
>     +       pp->flags |= G_PF_DIRECT_RECEIVE | G_PF_DIRECT_SEND;
>              pp->sectorsize = DEV_BSIZE;
>
>              zv = kmem_zalloc(sizeof(*zv), KM_SLEEP);
>     @@ -2171,18 +2172,20 @@ zvol_geom_start(struct bio *bp)
>              zvol_state_t *zv;
>              boolean_t first;
>
>     +       zv = bp->bio_to->private;
>     +       ASSERT(zv != NULL);
>              switch (bp->bio_cmd) {
>     +       case BIO_FLUSH:
>     +               if (curthread->td_no_sleeping != 0)
>     +                       goto enqueue;
>     +               zil_commit(zv->zv_zilog, ZVOL_OBJ);
>     +               g_io_deliver(bp, 0);
>     +               break;
>              case BIO_READ:
>              case BIO_WRITE:
>     -       case BIO_FLUSH:
>     -               zv = bp->bio_to->private;
>     -               ASSERT(zv != NULL);
>     -               mtx_lock(&zv->zv_queue_mtx);
>     -               first = (bioq_first(&zv->zv_queue) == NULL);
>     -               bioq_insert_tail(&zv->zv_queue, bp);
>     -               mtx_unlock(&zv->zv_queue_mtx);
>     -               if (first)
>     -                       wakeup_one(&zv->zv_queue);
>     +               if (curthread->td_no_sleeping != 0)
>     +                       goto enqueue;
>     +               zvol_strategy(bp);
>                      break;
>              case BIO_GETATTR:
>              case BIO_DELETE:
>     @@ -2190,6 +2193,15 @@ zvol_geom_start(struct bio *bp)
>                      g_io_deliver(bp, EOPNOTSUPP);
>                      break;
>              }
>     +       return;
>     +
>     +enqueue:
>     +       mtx_lock(&zv->zv_queue_mtx);
>     +       first = (bioq_first(&zv->zv_queue) == NULL);
>     +       bioq_insert_tail(&zv->zv_queue, bp);
>     +       mtx_unlock(&zv->zv_queue_mtx);
>     +       if (first)
>     +               wakeup_one(&zv->zv_queue);
>       }
>
>       static void
>     @@ -2364,6 +2376,7 @@ zvol_rename_minor(struct g_geom *gp, con
>              g_wither_provider(pp, ENXIO);
>
>              pp = g_new_providerf(gp, "%s/%s", ZVOL_DRIVER, newname);
>     +       pp->flags |= G_PF_DIRECT_RECEIVE | G_PF_DIRECT_SEND;
>              pp->sectorsize = DEV_BSIZE;
>              pp->mediasize = zv->zv_volsize;
>              pp->private = zv;
>
>


-- 
Alexander Motin