On Thu, Oct 27, 2022 at 11:00:44AM +0800, Ziyang Zhang wrote: > On 2022/10/26 19:29, Ming Lei wrote: > > [...] > >> > >> Intel(R) Xeon(R) Platinum 8369B CPU @ 2.70GHz 16 cores > >> 64GB MEM, CentOS 8, kernel 6.0+ > >> with IORING_SETUP_COOP_TASKRUN, without this kernel patch > >> > >> ucmd: io_uring_cmd_complete_in_task(), ublk_drv is a module > >> > >> ucmd-not-touch-pdu: use llist && do not touch 'cmd'/'pdu'/'io' in ublk_queue_rq() > >> > >> tw: task_work_add(), ublk is built-in. > >> > >> > >> -------- > >> fio test > >> > >> iodepth=128 numjobs=1 direct=1 bs=4k > >> > >> -------------------------------------------- > >> ublk loop target, the backend is a file. > >> > >> IOPS(k) > >> > >> type ucmd tw ucmd-not-touch-pdu > >> seq-read 54.1 53.8 53.6 > >> rand-read 52.0 52.0 52.0 > >> > >> -------------------------------------------- > >> ublk null target > >> IOPS(k) > >> > >> type ucmd tw ucmd-not-touch-pdu > >> seq-read 272 286 275 > >> rand-read 262 278 269 > >> > >> > >> ------------ > >> ublksrv test > >> > >> ------------- > >> ucmd > >> > >> running loop/001 > >> fio (ublk/loop( -f /root/work/ubdsrv/tests/tmp/ublk_loop_1G_BZ85U), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 66737 > >> randread: jobs 1, iops 64935 > >> randrw: jobs 1, iops read 32694 write 32710 > >> rw(512k): jobs 1, iops read 772 write 819 > >> > >> running null/001 > >> fio (ublk/null(), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 715863 > >> randread: jobs 1, iops 758449 > >> randrw: jobs 1, iops read 357407 write 357183 > >> rw(512k): jobs 1, iops read 5895 write 5875 > >> > >> ------------- > >> tw > >> > >> running loop/001 > >> fio (ublk/loop( -f /root/work/ubdsrv/tests/tmp/ublk_loop_1G_pvLTL), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 66856 > >> randread: jobs 1, iops 65015 > >> randrw: jobs 1, iops read 32751 write 32767 > >> rw(512k): jobs 1, iops read 776 write 823 > >> > >> running null/001 > >> fio (ublk/null(), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 739450 > >> randread: jobs 1, iops 787500 > >> randrw: jobs 1, iops read 372956 write 372831 > >> rw(512k): jobs 1, iops read 5798 write 5777 > >> > >> ------------- > >> ucmd-not-touch-pdu > >> > >> running loop/001 > >> fio (ublk/loop( -f /root/work/ubdsrv/tests/tmp/ublk_loop_1G_oH0eG), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 66754 > >> randread: jobs 1, iops 65032 > >> randrw: jobs 1, iops read 32776 write 32792 > >> rw(512k): jobs 1, iops read 772 write 818 > >> > >> running null/001 > >> fio (ublk/null(), libaio, bs 4k, dio, hw queues:1, uring_comp: 0, get_data: 0)... > >> randwrite: jobs 1, iops 725334 > >> randread: jobs 1, iops 741105 > >> randrw: jobs 1, iops read 360285 write 360047 > >> rw(512k): jobs 1, iops read 5770 write 5748 > >> > >> Not touching cmd/pdu/io in ublk_queue_rq() improves IOPS. > >> But it is worse than using task_work_add(). > > > > Thanks for the test! It is better to not share ucmd between > > ublk blk-mq io context and ubq daemon context, and we can > > improve it for using io_uring_cmd_complete_in_task(), and I > > have one patch by using the batch handing approach in > > io_uring_cmd_complete_in_task(). > > > > Another reason could be the extra __set_notify_signal() in > > __io_req_task_work_add() via task_work_add(). When task_work_add() > > is available, we just need to call __set_notify_signal() once > > for the whole batch, but it can't be done in case of using > > io_uring_cmd_complete_in_task(). > > > > Also the patch of 'use llist' is actually wrong since we have to > > call io_uring_cmd_complete_in_task() once in ->commit_rqs(), but > > that couldn't be easy because ucmd isn't available at that time. > > Yes, you are correct. > > > > > I think we may have to live with task_work_add() until the perf > > number is improved to same basically with io_uring_cmd_complete_in_task(). > > OK, we can keep task_work_add() && io_uring_cmd_complete_in_task(). > BTW, from test:loop/001, I think with real backends, the performance > gap between them seems not too big. Actually in VM created in my laptop, the gap isn't small on ublk-loop: 1) ublk-null, single job, change nr_hw_queue to 2 for using none scheduler [root@ktest-09 ublksrv]# make test T=null/001:null/004 make -C tests run T=null/001:null/004 R=10 D=tests/tmp/ make[1]: Entering directory '/root/git/ublksrv/tests' ./run_test.sh null/001:null/004 10 tests/tmp/ running null/001 fio (ublk/null(), libaio, dio, hw queues:2, io jobs: 1, uring_comp: 0, get_data: 0)... randwrite(4k): jobs 1, iops 1028774, cpu_util(29% 69%) randread(4k): jobs 1, iops 958598, cpu_util(27% 72%) randrw(4k): jobs 1, iops read 453382 write 453239, cpu_util(29% 70%) rw(512k): jobs 1, iops read 5264 write 5242, cpu_util(7% 6%) running null/004 fio (ublk/null(), libaio, dio, hw queues:2, io jobs: 1, uring_comp: 1, get_data: 0)... randwrite(4k): jobs 1, iops 950755, cpu_util(30% 69%) randread(4k): jobs 1, iops 855984, cpu_util(26% 73%) randrw(4k): jobs 1, iops read 439369 write 439287, cpu_util(29% 70%) rw(512k): jobs 1, iops read 5225 write 5202, cpu_util(7% 5%) 2) ublk-loop, single job, change nr_hw_queue to 2 for using none scheduler [root@ktest-09 ublksrv]# make test T=loop/001:loop/004 make -C tests run T=loop/001:loop/004 R=10 D=tests/tmp/ make[1]: Entering directory '/root/git/ublksrv/tests' ./run_test.sh loop/001:loop/004 10 tests/tmp/ running loop/001 fio (ublk/loop( -f /root/git/ublksrv/tests/tmp/ublk_loop_2G_STbdZ), libaio, dio, hw queues:2, io jobs: 1, uring_comp: 0, get_data: 0)... randwrite(4k): jobs 1, iops 163177, cpu_util(7% 20%) randread(4k): jobs 1, iops 141584, cpu_util(6% 14%) randrw(4k): jobs 1, iops read 75034 write 75148, cpu_util(7% 17%) rw(512k): jobs 1, iops read 1574 write 1663, cpu_util(3% 4%) running loop/004 fio (ublk/loop( -f /root/git/ublksrv/tests/tmp/ublk_loop_2G_AdrHl), libaio, dio, hw queues:2, io jobs: 1, uring_comp: 1, get_data: 0)... randwrite(4k): jobs 1, iops 142353, cpu_util(7% 19%) randread(4k): jobs 1, iops 133883, cpu_util(6% 14%) randrw(4k): jobs 1, iops read 72581 write 72691, cpu_util(7% 18%) rw(512k): jobs 1, iops read 929 write 981, cpu_util(2% 2%) Thanks, Ming
