On 15/12/2021 15:47, Jens Axboe wrote:
0000000000001ef0 <__blk_mq_delay_run_hw_queue>: [snip] 2024: a942dfb6 ldp x22, x23, [x29, #40] 2028: 2a1503e0 mov w0, w21 202c: 94000000 bl 0 <__msecs_to_jiffies> kblockd_mod_delayed_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work, 2030: aa0003e2 mov x2, x0 2034: 91010261 add x1, x19, #0x40 2038: 2a1403e0 mov w0, w20 203c: 94000000 bl 0 <kblockd_mod_delayed_work_on> I'm not sure if you would want to change so many APIs or if jiffies is sensible to pass or even any performance gain. Additionally Function blk_mq_delay_kick_requeue_list() would not see so much gain in such a change as msec value is not const. Any thoughts? Maybe testing performance would not do much harm.In general I totally agree with you, it'd be smarter to flip the conversion so it can be done in a more efficient manner.
At the same time, the queue delay running is not at all a fast path, so shouldn't really matter in practice.
ok, I just thought that from checking your change that we have a frequent msec_to_jiffies(0 [non const]) call in __blk_mq_delay_run_hw_queue() -> kblockd_mod_delayed_work_on().
Thanks, John
