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Re: [RFC v4 00/11] blkio: add libblkio BlockDriver
From: |
Stefan Hajnoczi |
Subject: |
Re: [RFC v4 00/11] blkio: add libblkio BlockDriver |
Date: |
Wed, 31 Aug 2022 15:44:10 -0400 |
On Tue, Aug 23, 2022 at 08:31:03PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> On 8/23/22 01:23, Stefan Hajnoczi wrote:
> > The remainder of the patch series reworks the existing QEMU
> > bdrv_register_buf()
> > API so virtio-blk emulation efficiently map guest RAM for libblkio - some
> > libblkio drivers require that I/O buffer memory is pre-registered (think
> > VFIO,
> > vhost, etc).
>
> Hi!
>
> So patches 01-11 are for performance optimization? Don't you have some
> performance measurements for it?
Hi Vladimir,
I ran the patches against qemu-storage-daemon's vhost-user-blk export
with iodepth=1 bs=512 to see the per-request overhead due to bounce
buffer allocation/mapping:
Name IOPS Error
bounce-buf 4373.81 ± 0.01%
registered-buf 13062.80 ± 0.67%
The BDRV_REQ_REGISTERED_BUF optimization version is about 3x faster.
Note that IOPS is low because the vhost-user-blk vq is not passed
through to the guest yet (Stefano is working on this). The guest is
also using interrupts, not polling (recent Linux virtio_blk.ko drivers
support poll queues).
I'll also include performance results in the next revision of the patch
series.
Stefan
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- [RFC v4 08/11] exec/cpu-common: add qemu_ram_get_fd(), (continued)
Re: [RFC v4 00/11] blkio: add libblkio BlockDriver, Vladimir Sementsov-Ogievskiy, 2022/08/23