From: Stefan Hajnoczi <stefanha@gmail.com>
To: Fam Zheng <famz@redhat.com>
Cc: qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
Ed Swierk <eswierk@skyportsystems.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] virtio: Report real progress in VQ aio poll handler
Date: Mon, 13 Feb 2017 16:35:12 +0000 [thread overview]
Message-ID: <20170213163512.GP10361@stefanha-x1.localdomain> (raw)
In-Reply-To: <20170209084047.7897-1-famz@redhat.com>
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On Thu, Feb 09, 2017 at 04:40:47PM +0800, Fam Zheng wrote:
> In virtio_queue_host_notifier_aio_poll, not all "!virtio_queue_empty()"
> cases are making true progress.
>
> Currently the offending one is virtio-scsi event queue, whose handler
> does nothing if no event is pending. As a result aio_poll() will spin on
> the "non-empty" VQ and take 100% host CPU.
>
> Fix this by reporting actual progress from virtio queue aio handlers.
>
> Reported-by: Ed Swierk <eswierk@skyportsystems.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
> hw/block/dataplane/virtio-blk.c | 4 ++--
> hw/block/virtio-blk.c | 12 ++++++++++--
> hw/scsi/virtio-scsi-dataplane.c | 14 +++++++-------
> hw/scsi/virtio-scsi.c | 14 +++++++++++---
> hw/virtio/virtio.c | 15 +++++++++------
> include/hw/virtio/virtio-blk.h | 2 +-
> include/hw/virtio/virtio-scsi.h | 6 +++---
> include/hw/virtio/virtio.h | 4 ++--
> 8 files changed, 45 insertions(+), 26 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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prev parent reply other threads:[~2017-02-13 16:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-09 8:40 [Qemu-devel] [PATCH] virtio: Report real progress in VQ aio poll handler Fam Zheng
2017-02-09 14:17 ` Ed Swierk
2017-02-09 14:58 ` Paolo Bonzini
2017-02-13 16:35 ` Stefan Hajnoczi [this message]
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