On Sat, Mar 18, 2023 at 10:09:52AM -0600, Jens Axboe wrote: > On 3/14/23 6:57?AM, Ming Lei wrote: > > Basically userspace can specify any sub-buffer of the ublk block request > > buffer from the fused command just by setting 'offset/len' > > in the slave SQE for running slave OP. This way is flexible to implement > > io mapping: mirror, stripped, ... > > > > The 3th & 4th patches enable fused slave support for the following OPs: > > > > OP_READ/OP_WRITE > > OP_SEND/OP_RECV/OP_SEND_ZC > > > > The other ublk patches cleans ublk driver and implement fused command > > for supporting zero copy. > > > > Follows userspace code: > > > > https://github.com/ming1/ubdsrv/tree/fused-cmd-zc-v2 > > Ran some quick testing here with qcow2. This is just done on my laptop > in kvm, so take them with a grain of salt, results may be better > elsewhere. > > Basline: > > 64k reads 98-100K IOPS 6-6.1GB/sec (ublk 100%, io_uring 9%) > 4k reads 670-680K IOPS 2.6GB/sec (ublk 65%, io_uring 44%) > > and with zerocopy enabled: > > 64k reads 184K IOPS 11.5GB/sec (ublk 91%, io_uring 12%) > 4k reads 730K IOPS 2.8GB/sec (ublk 73%, io_uring 48%) There are other ways to observe the boost: 1) loop over file in tmpfs - 1~2X in my test 2) nbd with local nbd server(nbdkit memory ) - less than 1X in my test 3) null - which won't call into fused command, but can evaluate page copy cost - 5+X in my test > > and with zerocopy and using SINGLE_ISSUER|COOP_TASKRUN for the ring: > > 64k reads 205K IOPS 12.8GB/sec (ublk 91%, io_uring 12%) > 4k reads 730K IOPS 2.8GB/sec (ublk 66%, io_uring 42%) Looks SINGLE_ISSUER|COOP_TASKRUN can get ~10% improvement, will look it. Thanks, Ming
