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

[Adrian Chadd]

Hi,

(I know this is bikeshedding, sorry!)

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 ?

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.

Thanks,



-adrian


On 25 August 2013 04:21, Alexander Motin <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;
>