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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