Hello, Is there a proper patch formatted variant of this where I can download and test? Or is it included in a released kernel already? I am seeing an issue, where one of the write-mostly disks in a 3 disk raid1 array consisting of one ssd and 2 spinning disks(write-mostly) is causing the mismatch_cnt to go as high as 1,5 million and a repair does not fix it. So this looks like a good potential resolver. Thanks, -Nik On 6/18/19 6:58 AM, Guoqing Jiang wrote: > > > On 6/18/19 12:41 PM, Song Liu wrote: >> On Mon, Jun 17, 2019 at 8:41 PM Guoqing Jiang <gqjiang@xxxxxxxx> wrote: >> <snip> >> >>>>> +}; >>>> Have we measured the performance overhead of this? >>>> The linear search for every IO worries me. >>> From array's view, I think the performance will not be impacted, >>> because write IO is complete >>> after it reached all the non-writemostly devices. >>> >> Hmm... How about the cpu utilization rate? Have you got chance >> to do some simple benchmarking? >> > > I can't see the impact of cpu in simple test, because it really > depends on > how slow the writemostly device is. > > And the modern multi-queue device (also flagged as writemostly) would > be fast enough to handle the write-behind IO in time, which means there > should only a few (or zero) elements in wb_list, but it is a potential > issue > which need to be addressed. > > Thanks, > Guoqing
