From: Stefan Hajnoczi <stefanha@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
linux-fsdevel@vger.kernel.org,
virtualization@lists.linux-foundation.org, miklos@szeredi.hu,
linux-kernel@vger.kernel.org, virtio-fs@redhat.com,
dgilbert@redhat.com
Subject: Re: [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time
Date: Mon, 9 Sep 2019 18:10:45 +0200 [thread overview]
Message-ID: <20190909161045.GD20875@stefanha-x1.localdomain> (raw)
In-Reply-To: <20190906101819-mutt-send-email-mst@kernel.org>
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On Fri, Sep 06, 2019 at 10:18:49AM -0400, Michael S. Tsirkin wrote:
> On Fri, Sep 06, 2019 at 10:17:05AM -0400, Vivek Goyal wrote:
> > On Fri, Sep 06, 2019 at 11:52:10AM +0100, Stefan Hajnoczi wrote:
> > > On Thu, Sep 05, 2019 at 03:48:49PM -0400, Vivek Goyal wrote:
> > > > +static void virtio_fs_drain_queue(struct virtio_fs_vq *fsvq)
> > > > +{
> > > > + WARN_ON(fsvq->in_flight < 0);
> > > > +
> > > > + /* Wait for in flight requests to finish.*/
> > > > + while (1) {
> > > > + spin_lock(&fsvq->lock);
> > > > + if (!fsvq->in_flight) {
> > > > + spin_unlock(&fsvq->lock);
> > > > + break;
> > > > + }
> > > > + spin_unlock(&fsvq->lock);
> > > > + usleep_range(1000, 2000);
> > > > + }
> > >
> > > I think all contexts that call this allow sleeping so we could avoid
> > > usleep here.
> >
> > usleep_range() is supposed to be used from non-atomic context.
> >
> > https://github.com/torvalds/linux/blob/master/Documentation/timers/timers-howto.rst
> >
> > What construct you are thinking of?
> >
> > Vivek
>
> completion + signal on vq callback?
Yes. Time-based sleep() is sub-optimal because we could wake up exactly
when in_flight is decremented from the vq callback. This avoids
unnecessary sleep wakeups and the extra time spent sleeping after
in_flight has been decremented.
Stefan
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next prev parent reply other threads:[~2019-09-09 16:11 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 19:48 [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Vivek Goyal
2019-09-05 19:48 ` [PATCH 01/18] virtiofs: Remove request from processing list before calling end Vivek Goyal
2019-09-06 10:40 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 02/18] virtiofs: Check whether hiprio queue is connected at submission time Vivek Goyal
2019-09-06 10:43 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 03/18] virtiofs: Pass fsvq instead of vq as parameter to virtio_fs_enqueue_req Vivek Goyal
2019-09-06 10:44 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 04/18] virtiofs: Check connected state for VQ_REQUEST queue as well Vivek Goyal
2019-09-06 10:45 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 05/18] Maintain count of in flight requests for VQ_REQUEST queue Vivek Goyal
2019-09-06 10:46 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 06/18] virtiofs: ->remove should not clean virtiofs fuse devices Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 07/18] virtiofs: Stop virtiofs queues when device is being removed Vivek Goyal
2019-09-06 10:47 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 08/18] virtiofs: Drain all pending requests during ->remove time Vivek Goyal
2019-09-06 10:52 ` Stefan Hajnoczi
2019-09-06 14:17 ` Vivek Goyal
2019-09-06 14:18 ` Michael S. Tsirkin
2019-09-09 16:10 ` Stefan Hajnoczi [this message]
2019-09-08 10:11 ` [Virtio-fs] " piaojun
2019-09-05 19:48 ` [PATCH 09/18] virtiofs: Add an helper to start all the queues Vivek Goyal
2019-09-06 10:54 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 10/18] virtiofs: Do not use device managed mem for virtio_fs and virtio_fs_vq Vivek Goyal
2019-09-06 10:56 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 11/18] virtiofs: stop and drain queues after sending DESTROY Vivek Goyal
2019-09-06 11:50 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 12/18] virtiofs: Use virtio_fs_free_devs() in error path Vivek Goyal
2019-09-06 11:51 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 13/18] virtiofs: Do not access virtqueue in request submission path Vivek Goyal
2019-09-06 11:52 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 14/18] virtiofs: Add a fuse_iqueue operation to put() reference Vivek Goyal
2019-09-06 12:00 ` Stefan Hajnoczi
2019-09-06 13:35 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 15/18] virtiofs: Make virtio_fs object refcounted Vivek Goyal
2019-09-06 12:03 ` Stefan Hajnoczi
2019-09-06 13:50 ` Vivek Goyal
2019-09-09 16:12 ` Stefan Hajnoczi
2019-09-08 11:10 ` [Virtio-fs] " piaojun
2019-09-09 15:35 ` Vivek Goyal
2019-09-05 19:48 ` [PATCH 16/18] virtiofs: Use virtio_fs_mutex for races w.r.t ->remove and mount path Vivek Goyal
2019-09-06 12:05 ` Stefan Hajnoczi
2019-09-06 13:51 ` Vivek Goyal
2019-09-09 16:13 ` Stefan Hajnoczi
2019-09-08 11:19 ` [Virtio-fs] " piaojun
2019-09-05 19:48 ` [PATCH 17/18] virtiofs: Remove TODO to quiesce/end_requests Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-05 19:48 ` [PATCH 18/18] virtiofs: Remove TODO item from virtio_fs_free_devs() Vivek Goyal
2019-09-06 12:06 ` Stefan Hajnoczi
2019-09-06 8:15 ` [PATCH 00/18] virtiofs: Fix various races and cleanups round 1 Miklos Szeredi
2019-09-06 10:36 ` Stefan Hajnoczi
2019-09-06 11:52 ` Miklos Szeredi
2019-09-06 12:08 ` Vivek Goyal
2019-09-06 13:55 ` Miklos Szeredi
2019-09-06 13:57 ` Michael S. Tsirkin
2019-09-06 14:11 ` Miklos Szeredi
2019-09-06 14:17 ` Michael S. Tsirkin
2019-09-08 11:53 ` [Virtio-fs] " piaojun
2019-09-09 16:14 ` Stefan Hajnoczi
2019-09-09 16:18 ` Michael S. Tsirkin
2019-09-09 23:52 ` piaojun
2019-09-06 13:37 ` Michael S. Tsirkin
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