From: Peter Xu <peterx@redhat.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
qemu-devel@nongnu.org, eric.auger@redhat.com, aik@ozlabs.ru
Subject: Re: [PATCH v2 3/3] vfio/pci: Add ioeventfd support
Date: Fri, 16 Mar 2018 12:40:17 +0800 [thread overview]
Message-ID: <20180316044017.GC2477@xz-mi> (raw)
In-Reply-To: <20180315213157.15150.86812.stgit@gimli.home>
On Thu, Mar 15, 2018 at 03:31:58PM -0600, Alex Williamson wrote:
> The ioeventfd here is actually irqfd handling of an ioeventfd such as
> supported in KVM. A user is able to pre-program a device write to
> occur when the eventfd triggers. This is yet another instance of
> eventfd-irqfd triggering between KVM and vfio. The impetus for this
> is high frequency writes to pages which are virtualized in QEMU.
> Enabling this near-direct write path for selected registers within
> the virtualized page can improve performance and reduce overhead.
> Specifically this is initially targeted at NVIDIA graphics cards where
> the driver issues a write to an MMIO register within a virtualized
> region in order to allow the MSI interrupt to re-trigger.
>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
next prev parent reply other threads:[~2018-03-16 4:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-15 21:31 [PATCH v2 0/3] vfio/pci: ioeventfd support Alex Williamson
2018-03-15 21:31 ` [PATCH v2 1/3] vfio/pci: Pull BAR mapping setup from read-write path Alex Williamson
2018-03-15 21:31 ` [PATCH v2 2/3] vfio/pci: Use endian neutral helpers Alex Williamson
2018-03-15 21:31 ` [PATCH v2 3/3] vfio/pci: Add ioeventfd support Alex Williamson
2018-03-16 4:40 ` Peter Xu [this message]
2018-03-19 9:09 ` [PATCH v2 0/3] vfio/pci: " Alexey Kardashevskiy
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