From: Alejandro Lucero <alejandro.lucero@netronome.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Thomas Monjalon <thomas.monjalon@6wind.com>,
Jason Wang <jasowang@redhat.com>, dev <dev@dpdk.org>,
huawei.xie@intel.com, yuanhan.liu@linux.intel.com
Subject: Re: [dpdk-dev] [PATCH 2/2] virtio: support IOMMU platform
Date: Sun, 4 Sep 2016 09:08:46 +0100 [thread overview]
Message-ID: <CAD+H991ohd4N_NAyL-pMgo8PkHbWXj67CitHGCXX3J=_1113Ng@mail.gmail.com> (raw)
In-Reply-To: <20160902202613-mutt-send-email-mst@kernel.org>
I know RedHat is working on a vIOMMU so I guess this work is related to
that effort, but it is a surprise virtio using IOMMU. I thought IOMMU just
made sense when using SRIOV. My second guess is using IOMMU with virtio is
a matter of security, but by other hand, virtio + IOMMU could imply serious
performance degradation when multiple VMs are in use. I'm talking about
IOMMU contention, exactly about IOTLB contention. This performance issue is
complex to describe or even analyze as there are several factors having an
impact on it. For example, 1GB hugepages can avoid most of it and the same
if TX & RX rings are not bigger than 256. So, my question: is RedHat aware
of this potential IOMMU contention which can limit scalability?
On Fri, Sep 2, 2016 at 6:26 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
> On Fri, Sep 02, 2016 at 03:04:56PM +0200, Thomas Monjalon wrote:
> > 2016-09-02 14:37, Jason Wang:
> > > Virtio pmd doesn't support VFIO in the past since devices bypass IOMMU
> > > completely. But recently, the work of making virtio device work with
> > > IOMMU is near to complete.
> >
> > Good news!
> > What are the requirements for Qemu and Linux version numbers please?
>
> I expect QEMU 2.8 and Linux 4.8 to have the support.
>
next prev parent reply other threads:[~2016-09-04 8:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-02 6:36 [dpdk-dev] [PATCH 1/2] net/virtio: support modern device id Jason Wang
2016-09-02 6:37 ` [dpdk-dev] [PATCH 2/2] virtio: support IOMMU platform Jason Wang
2016-09-02 13:04 ` Thomas Monjalon
2016-09-02 17:26 ` Michael S. Tsirkin
2016-09-04 8:08 ` Alejandro Lucero [this message]
2016-09-05 6:31 ` Jason Wang
2016-09-05 6:31 ` Jason Wang
2016-09-05 6:31 ` Jason Wang
2016-09-05 5:15 ` Jason Wang
2016-09-05 6:25 ` Jason Wang
2016-09-05 6:25 ` Jason Wang
2016-09-05 6:25 ` Jason Wang
[not found] ` <20160905071626.GM30752@yliu-dev.sh.intel.com>
2016-09-06 7:46 ` Yuanhan Liu
2016-09-07 4:53 ` Jason Wang
2016-09-02 12:57 ` [dpdk-dev] [PATCH 1/2] net/virtio: support modern device id Thomas Monjalon
2016-09-05 6:36 ` Jason Wang
2016-09-05 6:36 ` Jason Wang
2016-09-05 6:36 ` Jason Wang
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