On Wed, Dec 07, 2022 at 10:19:08AM +0800, Yu Kuai wrote: > Hi, > > 在 2022/12/07 2:15, Gulam Mohamed 写道: > > Use ktime to change the granularity of IO accounting in block layer from > > milli-seconds to nano-seconds to get the proper latency values for the > > devices whose latency is in micro-seconds. After changing the granularity > > to nano-seconds the iostat command, which was showing incorrect values for > > %util, is now showing correct values. > > This patch didn't correct the counting of io_ticks, just make the > error accounting from jiffies(ms) to ns. The problem that util can be > smaller or larger still exist. Agree. > > However, I think this change make sense consider that error margin is > much smaller, and performance overhead should be minimum. > > Hi, Ming, how do you think? I remembered that ktime_get() has non-negligible overhead, is there any test data(iops/cpu utilization) when running fio or t/io_uring on null_blk with this patch? Thanks, Ming
