[PATCH v7 4/9] nvme-multipath: add support for latency I/O policy

[John Garry]

On 10/08/2026 18:25, Nilay Shroff wrote:
>> 
>> iops: (groupid=0, jobs=10): err= 0: pid=821: Mon Aug 10 08:08:28 2026
>>     read: IOPS=9239, BW=36.1MiB/s (37.8MB/s)(1434MiB/39744msec)
>>       slat (usec): min=25, max=110836, avg=129.22, stdev=537.18
>> 
>> Note that I do have many heavy kernel debug options enabled, like kasan and kmemleak, which may influence this.
>> 
> 
> Thanks for testing. Given that you're running with KASAN, kmemleak, and other
> heavy debug options enabled, I think this is expected. Those configurations
> can significantly increase I/O completion latency, causing some samples to
> exceed the 1-second threshold. The warning is also rate-limited to avoid
> flooding the log. That said, still if it's causing a lot of noise in the logs
> then we could change it to dev_dbg_ratelimited() from dev_warn_ratelimited().

Note they these warnings go away when I turn off those debug options, as 
expected.

The max latency I was seeing was ~1.2 seconds. Maybe you can just 
increase this limit for ignoring the sample. Or make it a 
dev_warn_once(). Or control the warn print rate with DEFINE_RATELIMIT_STATE.