On Fri, Dec 08, 2023 at 10:00:36AM +0800, Ming Lei wrote: > On Thu, Dec 07, 2023 at 12:31:05PM +0800, Li Feng wrote: > > virtio-blk is generally used in cloud computing scenarios, where the > > performance of virtual disks is very important. The mq-deadline scheduler > > has a big performance drop compared to none with single queue. In my tests, > > mq-deadline 4k readread iops were 270k compared to 450k for none. So here > > the default scheduler of virtio-blk is set to "none". > > The test result shows you may not test HDD. backing of virtio-blk. > > none can lose IO merge capability more or less, so probably sequential IO perf > drops in case of HDD backing. More of a curiosity, as I don't immediately even have an HDD to test with! Isn't it more useful for the host providing the backing HDD use an appropriate IO scheduler? virtio-blk has similiarities with a stacking block driver, and we usually don't need to stack IO schedulers.
