From: Tiwei Bie <tiwei.bie@intel.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: mst@redhat.com, jasowang@redhat.com, pbonzini@redhat.com,
virtualization@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, dan.daly@intel.com,
cunming.liang@intel.com, zhihong.wang@intel.com
Subject: Re: [RFC] virtio: support VIRTIO_F_IO_BARRIER
Date: Thu, 3 May 2018 21:26:47 +0800 [thread overview]
Message-ID: <20180503132647.yfulyzbygdfgu2or@debian> (raw)
In-Reply-To: <20180503090652.GB5301@stefanha-x1.localdomain>
On Thu, May 03, 2018 at 10:06:52AM +0100, Stefan Hajnoczi wrote:
> On Thu, May 03, 2018 at 10:59:55AM +0800, Tiwei Bie wrote:
> > This patch introduces the support for VIRTIO_F_IO_BARRIER.
> > When this feature is negotiated, driver will use the barriers
> > suitable for hardware devices.
> >
> > Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
>
> I should have thought of this earlier, but why is a new feature bit
> necessary? If a hardware virtio device is in use, then the device
> should already negotiate VIRTIO_F_IOMMU_PLATFORM (i.e. use DMA APIs and
> IOMMU callbacks).
>
> Does disabling weak_barriers when VIRTIO_F_IOMMU_PLATFORM is set solve
> the problem?
The VIRTIO_F_IOMMU_PLATFORM feature can be set when the
device is implemented in software. And I think we don't
want the performance drop in this case.
Best regards,
Tiwei Bie
next prev parent reply other threads:[~2018-05-03 13:26 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-03 2:59 Tiwei Bie
2018-05-03 7:30 ` Jason Wang
2018-05-03 8:30 ` Tiwei Bie
2018-05-03 9:09 ` Jason Wang
2018-05-03 9:58 ` Tiwei Bie
2018-05-03 12:57 ` Jason Wang
2018-05-03 9:06 ` Stefan Hajnoczi
2018-05-03 13:26 ` Tiwei Bie [this message]
2018-05-03 13:50 ` Stefan Hajnoczi
2018-05-03 17:57 ` Michael S. Tsirkin
2018-05-04 1:14 ` Tiwei Bie
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