From: Wei Wang <wei.w.wang@intel.com>
To: Daniel Verkamp <dverkamp@chromium.org>,
virtualization@lists.linux-foundation.org
Cc: Liang Li <liang.z.li@intel.com>, "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH] virtio-balloon: request nvqs based on features
Date: Tue, 17 Dec 2019 10:00:30 +0800 [thread overview]
Message-ID: <5DF836BE.4040108@intel.com> (raw)
In-Reply-To: <20191216231429.38202-1-dverkamp@chromium.org>
On 12/17/2019 07:14 AM, Daniel Verkamp wrote:
> After 86a559787e6f ("virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT"),
> the virtio-balloon device unconditionally specifies 4 virtqueues as the
> argument to find_vqs(), which means that 5 MSI-X vectors are required in
> order to assign one vector per VQ plus one for configuration changes.
>
> However, in cases where the virtio device only provides exactly as many
> MSI-X vectors as required for the features it implements (e.g. 3 for the
> basic configuration of inflate + deflate + config), this results in the
> selection of the fallback configuration where one interrupt vector is
> used for all VQs instead of having one VQ per vector.
I'm not sure if I get the above. Virtio won't do any vq allocation for
the one that has "callbacks[i] = NULL", so no msi-x vector will be
assigned for it.
Btw, did you trigger any bug with the existing code?
Best,
Wei
next prev parent reply other threads:[~2019-12-17 2:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 23:14 [PATCH] virtio-balloon: request nvqs based on features Daniel Verkamp
2019-12-17 2:00 ` Wei Wang [this message]
2019-12-17 9:11 ` Cornelia Huck
2019-12-17 14:14 ` Michael S. Tsirkin
2019-12-17 19:04 ` Daniel Verkamp
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