On Tue, Nov 17, 2020 at 11:28 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
> On Tue, Nov 17, 2020 at 11:01:49AM +0800, Weiping Zhang wrote:
> > Hi Jens,
> >
> > Ping
>
> Hello Weiping,
>
> Not sure we have to fix this issue, and adding blk_mq_queue_inflight()
> back to IO path brings cost which turns out to be visible, and I did
> get soft lockup report on Azure NVMe because of this kind of cost.
>
Have you test v5, this patch is different from v1, the v1 gets
inflight for each IO,
v5 has changed to get inflight every jiffer.
If for v5, can we reproduce it on null_blk ?
> BTW, suppose the io accounting issue needs to be fixed, just wondering
> why not simply revert 5b18b5a73760 ("block: delete part_round_stats and
> switch to less precise counting"), and the original way had been worked
> for decades.
>
This patch is more better than before, it will break early when find there is
inflight io on any cpu, for the worst case(the io in running on the last cpu),
it iterates all cpus.
>
> Thanks,
> Ming
>
