On Fri, Jan 24, 2025 at 06:30:19PM +0900, Damien Le Moal wrote: > On 1/10/25 21:34, Ming Lei wrote: > >> It is easy to extend rublk/zoned in this way with io_uring io emulation, :-) > > > > Here it is: > > > > https://github.com/ublk-org/rublk/commits/file-backed-zoned/ > > > > Top two commits implement the feature by command line `--path $zdir`: > > > > [rublk]# git diff --stat=80 HEAD^^... > > src/zoned.rs | 397 +++++++++++++++++++++++++++++++++++++++++++++++---------- > > tests/basic.rs | 49 ++++--- > > 2 files changed, 363 insertions(+), 83 deletions(-) > > > > It takes 280 new LoC: > > > > - support both ram-back and file-back > > - completely async io_uring IO emulation for zoned read/write IO > > - include selftest code for running mkfs.btrfs/mount/read & write IO/umount > > Hi Ming, > > My apologies for the late reply. Conference travel kept me busy. > Thank you for doing this. I gave it a try and measured the performance for some > write workloads (using current Linus tree which includes the block PR for 6.14). > The zloop results shown here are with a slightly tweaked version (not posted) > that changes to using a work item per command instead of having a single work > for all commands. > > 1 queue: > ======== > +-------------------+-------------------+ > | ublk (IOPS / BW) | zloop (IOPS / BW) | > +----------------------------+-------------------+-------------------+ > | QD=1, 4K rnd wr, 1 job | 11.7k / 47.8 MB/s | 15.8k / 53.0 MB/s | > | QD=32, 4K rnd wr, 8 jobs | 63.4k / 260 MB/s | 101k / 413 MB/s | I can't reproduce the above two, actually not observe obvious difference between rublk/zoned and zloop in my test VM. Maybe rublk works at debug mode, which reduces perf by half usually. And you need to add device via 'cargo run -r -- add zoned' for using release mode. Actually there is just single io_uring_enter() running in each ublk queue pthread, perf should be similar with kernel IO handling, and the main extra load is from the single syscall kernel/user context switch and IO data copy, and data copy effect can be neglected in small io size usually(< 64KB). > | QD=32, 128K rnd wr, 1 job | 5008 / 656 MB/s | 5993 / 786 MB/s | > | QD=32, 128K seq wr, 1 job | 2636 / 346 MB/s | 5393 / 707 MB/s | ublk 128K BS may be a little slower since there is one extra copy. > +----------------------------+-------------------+-------------------+ > > 8 queues: > ========= > +-------------------+-------------------+ > | ublk (IOPS / BW) | zloop (IOPS / BW) | > +----------------------------+-------------------+-------------------+ > | QD=1, 4K rnd wr, 1 job | 9699 / 39.7 MB/s | 16.7k / 68.6 MB/s | > | QD=32, 4K rnd wr, 8 jobs | 58.2k / 238 MB/s | 108k / 444 MB/s | > | QD=32, 128K rnd wr, 1 job | 4160 / 545 MB/s | 5715 / 749 MB/s | > | QD=32, 128K seq wr, 1 job | 3274 / 429 MB/s | 5934 / 778 MB/s | > +----------------------------+-------------------+-------------------+ > > As you can see, zloop is generally much faster. This shows the best results from > several runs as performance variation from one run to another can be significant > (for both ublk and zloop). > > But as mentioned before, since this is intended to be a test tool for file > systems, performance is not the primary goal here (though the higher the better > as that shortens test times). Simplicity is. And as Ted also stated, introducing > a ublk and rust dependency in xfstests is far from ideal. Simplicity need to be observed from multiple dimensions, 300 vs. 1500 LoC has shown something already, IMO. Thanks, Ming
