On 26/10/2015 12:50, Andrey Korolyov wrote: > Hi, > > during the test against generic storage backend with NBD frontend we > found that the virtio block device is always splitting a single read > range request to 4k ones, bringing the overall performance of the > sequential reads far below virtio-scsi. Random reads are going > relatively well on small blocks due to small overhead comparing to > sequential ones and writes are ok in all cases. Multiread slightly > improves the situation, but it would be nice to see complete > pass-through of range read requests down to backend without an > intermediate splitting. > > Samples measured on an NBD backend during 128k sequential reads for > both virtio-blk and virtio-scsi are attached. Please let me know if it > looks like that I missed something or this behavior is plainly wrong.
How does the blktrace look like in the guest? Paolo
