Messages in this thread | | | Subject | Re: [PATCH RFT 0/3] blk-mq: Optimise blk_mq_queue_tag_busy_iter() for shared tags | From | John Garry <> | Date | Thu, 25 Nov 2021 14:09:33 +0000 |
| |
On 25/11/2021 13:46, Kashyap Desai wrote: >> John - >> >> I will try something this week and let you know. > John - I tested patchset and looks good. Issue reported at below thread is > fixed. > https://lore.kernel.org/linux-block/e4e92abbe9d52bcba6b8cc6c91c442cc@mail.gmail.com/ > > Here is perf top data. > > 5.70% [megaraid_sas] [k] complete_cmd_fusion > 3.80% [megaraid_sas] [k] > megasas_build_and_issue_cmd_fusion > 2.75% [kernel] [k] syscall_return_via_sysret > 2.68% [kernel] [k] entry_SYSCALL_64 > 2.22% [kernel] [k] io_submit_one > 2.19% [megaraid_sas] [k] megasas_build_ldio_fusion > 1.95% [kernel] [k] llist_add_batch > 1.80% [kernel] [k] llist_reverse_order > 1.79% [kernel] [k] scsi_complete > 1.73% [kernel] [k] scsi_queue_rq > 1.66% [kernel] [k] check_preemption_disabled > 1.37% [megaraid_sas] [k] megasas_queue_command > 1.16% [kernel] [k] native_irq_return_iret > 1.11% [kernel] [k] aio_complete_rw > 1.07% [kernel] [k] read_tsc > 1.06% fio [.] __fio_gettime > 1.05% [kernel] [k] flush_smp_call_function_queue > 1.03% [kernel] [k] blk_complete_reqs > 1.00% [kernel] [k] blk_mq_free_request > 0.98% [kernel] [k] sbitmap_get > > > I will continue testing and let you know how it goes.
ok, good to know, thanks. But I would still like to know what is triggering blk_mq_queue_tag_busy_iter() so often. Indeed, as mentioned in this cover letter, this function was hardly optimised before for shared sbitmap.
And any opinion whether we would want this as a fix? Information requested above would help explain why we would need it as a fix.
Cheers, John
| |