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From: Wei Wang <wei.w.wang@intel.com>
To: Jason Wang <jasowang@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>
Cc: "virtio-dev@lists.oasis-open.org"
	<virtio-dev@lists.oasis-open.org>,
	"stefanha@gmail.com" <stefanha@gmail.com>,
	"armbru@redhat.com" <armbru@redhat.com>,
	"jan.scheurich@ericsson.com" <jan.scheurich@ericsson.com>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	"marcandre.lureau@gmail.com" <marcandre.lureau@gmail.com>,
	"pbonzini@redhat.com" <pbonzini@redhat.com>
Subject: Re: [Qemu-devel] [virtio-dev] Re: [PATCH v1] virtio-net: enable configurable tx queue size
Date: Tue, 13 Jun 2017 14:13:14 +0800	[thread overview]
Message-ID: <593F827A.9000106@intel.com> (raw)
In-Reply-To: <fce1c1be-4105-3fd9-c734-987b85376cf9@redhat.com>

On 06/13/2017 11:59 AM, Jason Wang wrote:
>
> On 2017年06月13日 11:55, Jason Wang wrote:
>> The issue is what if there's a mismatch of max #sgs between qemu and
>> vhost?
>>
>>> When the vhost backend is used, QEMU is not involved in the data
>>> path. The vhost backend
>>> directly gets what is offered by the guest from the vq.
> FYI, qemu will try to fallback to userspace if there's something wrong
> with vhost-kernel (e.g the IOMMU support). This doesn't work for
> vhost-user actually, but it works for vhost-kernel.
>
> Thanks
>

That wouldn't be a problem. When it falls back to the QEMU backend,
the "max_chain_size" will be set according to the QEMU backend
(e.g. 1023). Guest will read the max_chain_size register.

Best,
Wei

  reply	other threads:[~2017-06-13  6:11 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-05  8:57 [Qemu-devel] [PATCH v1] virtio-net: enable configurable tx queue size Wei Wang
2017-06-05 15:38 ` Michael S. Tsirkin
2017-06-05 15:41   ` Eric Blake
2017-06-05 15:45     ` Michael S. Tsirkin
2017-06-06  3:32   ` Wei Wang
2017-06-07  1:04   ` Wei Wang
2017-06-08 19:01     ` Michael S. Tsirkin
2017-06-09  3:00       ` Wei Wang
2017-06-12  9:30         ` [Qemu-devel] [virtio-dev] " Wei Wang
2017-06-12 20:43           ` Michael S. Tsirkin
2017-06-13  3:10             ` Wei Wang
2017-06-13  3:19               ` Jason Wang
2017-06-13  3:51                 ` Wei Wang
2017-06-13  3:55                   ` Jason Wang
2017-06-13  3:59                     ` Jason Wang
2017-06-13  6:13                       ` Wei Wang [this message]
2017-06-13  6:31                         ` Jason Wang
2017-06-13  7:49                           ` [Qemu-devel] [virtio-dev] " Wei Wang
2017-06-13  6:08                     ` [Qemu-devel] " Wei Wang
2017-06-13  6:29                       ` [Qemu-devel] [virtio-dev] " Jason Wang
2017-06-13  7:17                         ` Wei Wang
2017-06-13  9:04                           ` Jason Wang
2017-06-13  9:50                             ` Wei Wang
2017-06-13 10:46                               ` Jason Wang
2017-06-14 11:26                                 ` Jason Wang
2017-06-14 15:22                                   ` Michael S. Tsirkin
2017-06-15  4:16                                     ` Jason Wang
2017-06-15  6:52                                       ` [Qemu-devel] [virtio-dev] " Wei Wang
2017-06-16  3:22                                         ` Michael S. Tsirkin
2017-06-16  8:57                                           ` Jason Wang
2017-06-16 10:10                                             ` Wei Wang
2017-06-16 15:15                                               ` Michael S. Tsirkin
2017-06-17  8:37                                                 ` Wei Wang
2017-06-18 19:46                                                   ` Michael S. Tsirkin
2017-06-19  7:40                                                     ` Wei Wang
2017-06-16 15:19                                             ` Michael S. Tsirkin
2017-06-16 17:04                                               ` Maxime Coquelin
2017-06-16 20:33                                                 ` Michael S. Tsirkin
2017-06-05 15:47 ` [Qemu-devel] " Michael S. Tsirkin

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