From: "Michael S. Tsirkin" <mst@redhat.com>
To: Wei Wang <wei.w.wang@intel.com>
Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
linux-mm@kvack.org, mhocko@kernel.org, akpm@linux-foundation.org,
pbonzini@redhat.com, liliang.opensource@gmail.com,
yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com,
riel@redhat.com
Subject: Re: [PATCH v23 2/2] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ
Date: Wed, 24 Jan 2018 19:32:59 +0200 [thread overview]
Message-ID: <20180124193217-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <5A681E03.1030007@intel.com>
On Wed, Jan 24, 2018 at 01:47:47PM +0800, Wei Wang wrote:
> On 01/24/2018 01:01 PM, Michael S. Tsirkin wrote:
> > On Wed, Jan 24, 2018 at 10:50:27AM +0800, Wei Wang wrote:
> > This will not DTRT in all cases. It's quite possible
> > that host does not need the kick when ring is half full but
> > does need it later when ring is full.
> > You can kick at ring half full as optimization but you absolutely
> > still must kick on ring full. Something like:
> >
> > if (vq->num_free == virtqueue_get_vring_size(vq) / 2 ||
> > vq->num_free <= 2)
>
> Right. Would "if (vq->num_free < virtqueue_get_vring_size(vq) / 2" be
> better?
>
>
> Best,
> Wei
It gives more kicks ... this reminds me, you need to validate
that vring size is at least 2, otherwise fail probe.
--
MST
prev parent reply other threads:[~2018-01-24 17:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-24 2:50 [PATCH v23 0/2] Virtio-balloon: support free page reporting Wei Wang
2018-01-24 2:50 ` [PATCH v23 1/2] mm: support reporting free page blocks Wei Wang
2018-01-24 2:50 ` [PATCH v23 2/2] virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_VQ Wei Wang
2018-01-24 5:01 ` Michael S. Tsirkin
2018-01-24 5:47 ` Wei Wang
2018-01-24 17:32 ` Michael S. Tsirkin [this message]
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