From: "Michael S. Tsirkin" <mst@redhat.com>
To: "Gonglei (Arei)" <arei.gonglei@huawei.com>
Cc: "stefanha@redhat.com" <stefanha@redhat.com>,
"jasowang@redhat.com" <jasowang@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"virtio-dev@lists.oasis-open.org"
<virtio-dev@lists.oasis-open.org>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Lilijun (Jerry)" <jerry.lilijun@huawei.com>,
"Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Subject: Re: Can we increase vring size over 1024?
Date: Fri, 2 Sep 2016 20:32:36 +0300 [thread overview]
Message-ID: <20160902201909-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <33183CC9F5247A488A2544077AF19020B03B318E@SZXEMA503-MBS.china.huawei.com>
On Fri, Sep 02, 2016 at 06:55:35AM +0000, Gonglei (Arei) wrote:
> Hi Michael & all,
>
> Michael, you made a presentation about the virto 1.1's new features in KVM Forum last week.
> That's wonderful!
>
> And I'd like to know can we increase vring size over 1024, such as 4096 or 8192?
>
> My colleage had asked the same question in 2014, but she didn't get a definite answare,
> So, I want to rewake up the dissusstion about this. Becase for the virtio-crypto device,
> I also need to increase the vring size to get better performance and thoughput, but the Qemu
> side limit the thought as VIRTQUEUE_MAX_SIZE is 1024.
>
> [QA-virtio]:Why vring size is limited to 1024?
> http://qemu.11.n7.nabble.com/QA-virtio-Why-vring-size-is-limited-to-1024-td292450.html
>
> Avi Kivity said that google cloud exposed the vring size to 16k.
>
> Regards,
> -Gonglei
Fundamentally, the reason is that the ring size
currently also sets the max s/g list length, and linux
hosts can't support bigger lists.
We should fix that in 1.1.
--
MST
next prev parent reply other threads:[~2016-09-02 17:32 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-02 6:55 Can we increase vring size over 1024? Gonglei (Arei)
2016-09-02 13:39 ` [Qemu-devel] " Stefan Hajnoczi
2016-09-05 3:21 ` 答复: " Lilijun (Jerry)
2016-09-05 16:18 ` 答复: [Qemu-devel] " Michael S. Tsirkin
2016-09-05 20:20 ` Stefan Hajnoczi
2016-09-02 17:32 ` Michael S. Tsirkin [this message]
2016-09-03 4:20 ` Gonglei (Arei)
2016-09-04 1:31 ` Michael S. Tsirkin
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