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RFC Google extension to improve qemu-nvme performance

Ming Lin linux-nvme qemu-devel virtualization 1 version New

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  1. v1 RFC Latest0 of 2 patches 0 repliesNew

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Cover letter [RFC PATCH 0/2] Google extension to improve qemu-nvme performance

Hi Rob & Mihai,

I wrote vhost-nvme patches on top of Christoph's NVMe target. vhost-nvme still uses mmio. So the guest OS can run unmodified NVMe driver. But the tests I have done didn't show competitive performance compared to virtio-blk/virtio-scsi. The bottleneck is in mmio. Your nvme vendor extension patches reduces greatly the number of MMIO writes. So I'd like to push it upstream.

I port these 2 patches to newer kernel and qemu.
I use ram disk as backend to compare performance.

qemu-nvme: 29MB/s
qemu-nvme+google-ext: 100MB/s
virtio-blk: 174MB/s
virtio-scsi: 118MB/s

I'll show you qemu-vhost-nvme+google-ext number later.

root at guest:~# cat test.job
[global]
bs=4k
ioengine=libaio
iodepth=64
direct=1
runtime=120
time_based
rw=randread
norandommap
group_reporting
gtod_reduce=1
numjobs=2

[job1]
filename=/dev/nvme0n1
#filename=/dev/vdb
#filename=/dev/sda
rw=read

Patches also available at:
kernel:
https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=nvme-google-ext
qemu:
http://www.minggr.net/cgit/cgit.cgi/qemu/log/?h=nvme-google-ext

Thanks,
Ming

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