| Message ID | 20220208063707.4781-2-xiaoguang.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [1/2] scsi: add scsi_done_direct() helper | expand |
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c index 4407b56aa6d1..ce414fbdbae6 100644 --- a/drivers/target/loopback/tcm_loop.c +++ b/drivers/target/loopback/tcm_loop.c @@ -70,8 +70,12 @@ static void tcm_loop_release_cmd(struct se_cmd *se_cmd) if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) kmem_cache_free(tcm_loop_cmd_cache, tl_cmd); - else - scsi_done(sc); + else { + if (unlikely(in_interrupt())) + scsi_done(sc); + else + scsi_done_direct(sc); + } } static int tcm_loop_show_info(struct seq_file *m, struct Scsi_Host *host)
Tcm_loop uses workqueue to end requests, which is non-interrupt context, then we can complete request directly instead deferring it to softirq. The call graph likes below: blk_mq_complete_request_remote+1 blk_mq_complete_request+14 target_put_sess_cmd+294 transport_generic_free_cmd+93 target_complete_ok_work+251 process_one_work+482 worker_thread+80 kthread+361 ret_from_fork+31 Use tcm_loop and tcmu(backstore is file) to evaluate performance, fio job: [global] filename=/dev/sdb direct=1 runtime=30 thread=1 norandommap=1 time_based numjobs=1 rw=randread iodepth=32 ioengine=libaio Without this patch: bs 4k READ: bw=319MiB/s (334MB/s), 319MiB/s-319MiB/s (334MB/s-334MB/s), io=9563MiB (10.0GB), run=30001-30001msec bs 8k: READ: bw=611MiB/s (641MB/s), 611MiB/s-611MiB/s (641MB/s-641MB/s), io=17.9GiB (19.2GB), run=30001-30001msec bs 16k: READ: bw=1109MiB/s (1163MB/s), 1109MiB/s-1109MiB/s (1163MB/s-1163MB/s), io=32.5GiB (34.9GB), run=30001-30001msec bs 32k: READ: bw=2200MiB/s (2306MB/s), 2200MiB/s-2200MiB/s (2306MB/s-2306MB/s), io=64.4GiB (69.2GB), run=30001-30001msec With this patch: bs 4k: READ: bw=344MiB/s (361MB/s), 344MiB/s-344MiB/s (361MB/s-361MB/s), io=10.1GiB (10.8GB), run=30001-30001msec bs 8k: READ: bw=651MiB/s (682MB/s), 651MiB/s-651MiB/s (682MB/s-682MB/s), io=19.1GiB (20.5GB), run=30001-30001msec bs 16k: READ: bw=1248MiB/s (1308MB/s), 1248MiB/s-1248MiB/s (1308MB/s-1308MB/s), io=36.6GiB (39.3GB), run=30001-30001msec bs 32k: READ: bw=2456MiB/s (2576MB/s), 2456MiB/s-2456MiB/s (2576MB/s-2576MB/s), io=71.0GiB (77.3GB), run=30001-30001msec We can get throughput improvement. Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> --- drivers/target/loopback/tcm_loop.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)