From: Jason Wang <jasowang@redhat.com>
To: Zha Bin <zhabin@linux.alibaba.com>, linux-kernel@vger.kernel.org
Cc: virtio-dev@lists.oasis-open.org, slp@redhat.com, mst@redhat.com,
jing2.liu@linux.intel.com, qemu-devel@nongnu.org,
chao.p.peng@linux.intel.com, gerry@linux.alibaba.com
Subject: Re: [PATCH v2 4/5] virtio-mmio: add MSI interrupt feature support
Date: Tue, 11 Feb 2020 11:17:38 +0800 [thread overview]
Message-ID: <0c71ff9d-1a7f-cfd2-e682-71b181bdeae4@redhat.com> (raw)
In-Reply-To: <4c3d13be5a391b1fc50416838de57d903cbf8038.1581305609.git.zhabin@linux.alibaba.com>
On 2020/2/10 下午5:05, Zha Bin wrote:
> From: Liu Jiang<gerry@linux.alibaba.com>
>
> Userspace VMMs (e.g. Qemu microvm, Firecracker) take advantage of using
> virtio over mmio devices as a lightweight machine model for modern
> cloud. The standard virtio over MMIO transport layer only supports one
> legacy interrupt, which is much heavier than virtio over PCI transport
> layer using MSI. Legacy interrupt has long work path and causes specific
> VMExits in following cases, which would considerably slow down the
> performance:
>
> 1) read interrupt status register
> 2) update interrupt status register
> 3) write IOAPIC EOI register
>
> We proposed to add MSI support for virtio over MMIO via new feature
> bit VIRTIO_F_MMIO_MSI[1] which increases the interrupt performance.
>
> With the VIRTIO_F_MMIO_MSI feature bit supported, the virtio-mmio MSI
> uses msi_sharing[1] to indicate the event and vector mapping.
> Bit 1 is 0: device uses non-sharing and fixed vector per event mapping.
> Bit 1 is 1: device uses sharing mode and dynamic mapping.
I believe dynamic mapping should cover the case of fixed vector?
Thanks
next prev parent reply other threads:[~2020-02-11 3:18 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 9:05 [PATCH v2 0/5] virtio mmio specification enhancement Zha Bin
2020-02-10 9:05 ` [PATCH v2 1/5] virtio-mmio: add notify feature for per-queue Zha Bin
2020-02-11 10:50 ` Michael S. Tsirkin
2020-02-11 11:33 ` Michael S. Tsirkin
2020-02-12 3:39 ` Jason Wang
2020-02-12 8:18 ` Michael S. Tsirkin
2020-02-12 8:53 ` Jason Wang
2020-02-12 9:33 ` Jason Wang
2020-02-12 9:55 ` Michael S. Tsirkin
2020-02-13 3:38 ` Jason Wang
2020-02-10 9:05 ` [PATCH v2 2/5] virtio-mmio: refactor common functionality Zha Bin
2020-02-11 11:19 ` Michael S. Tsirkin
2020-02-12 2:58 ` [virtio-dev] " Liu, Jing2
2020-02-12 7:29 ` Michael S. Tsirkin
2020-02-10 9:05 ` [PATCH v2 3/5] virtio-mmio: create a generic MSI irq domain Zha Bin
2020-02-11 11:16 ` Michael S. Tsirkin
2020-02-12 7:40 ` Michael S. Tsirkin
2020-02-10 9:05 ` [PATCH v2 4/5] virtio-mmio: add MSI interrupt feature support Zha Bin
2020-02-11 3:17 ` Jason Wang [this message]
2020-02-11 3:35 ` [virtio-dev] " Liu, Jing2
2020-02-11 4:02 ` Jason Wang
2020-02-11 6:02 ` Liu, Jing2
2020-02-11 7:40 ` Jason Wang
2020-02-11 11:58 ` Michael S. Tsirkin
2020-02-11 12:04 ` Jason Wang
2020-02-11 12:08 ` Michael S. Tsirkin
2020-02-11 12:18 ` Jason Wang
2020-02-11 14:00 ` Michael S. Tsirkin
2020-02-12 9:03 ` Jason Wang
2020-02-12 9:15 ` Michael S. Tsirkin
2020-02-12 3:54 ` Liu, Jing2
2020-02-12 7:33 ` Michael S. Tsirkin
2020-02-12 9:06 ` Jason Wang
2020-02-12 9:16 ` Michael S. Tsirkin
2020-02-13 3:40 ` Jason Wang
2020-02-11 11:21 ` Michael S. Tsirkin
2020-02-11 11:11 ` Michael S. Tsirkin
2020-02-10 9:05 ` [PATCH v2 5/5] x86: virtio-mmio: support virtio-mmio with MSI for x86 Zha Bin
2020-02-11 11:14 ` Michael S. Tsirkin
2020-02-10 11:44 ` [PATCH v2 0/5] virtio mmio specification enhancement Michael S. Tsirkin
2020-02-11 16:05 ` Chao Peng
2020-02-11 10:57 ` Michael S. Tsirkin
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