Hello, On Wed, Apr 24, 2024 at 12:36:45AM +0000, Shinichiro Kawasaki wrote: > Hello Tejun, thanks for the fix. I confirmed that the number of in-flight > works > become larger than 8 during the unmount operation. > > total infl CPUtime CPUitsv CMW/RPR mayday > rescued > dmz_cwq_dmz_dml_072 613 33 4.6 - 0 0 > 0 > > total infl CPUtime CPUitsv CMW/RPR mayday > rescued > dmz_cwq_dmz_dml_072 617 33 4.7 - 0 0 > 0 > > total infl CPUtime CPUitsv CMW/RPR mayday > rescued > dmz_cwq_dmz_dml_072 619 33 4.8 - 0 0 > 0 > > > Also I measured xfs unmount time of 10 times. Its avarage is as follows. > > Kernel | Unmount time > ----------------------+-------------- > v6.8 | 29m 3s > v6.9-rc2 | 34m 17s > v6.9-rc2 + Tejun fix | 30m 55s > > We can see that the fix reduced the unmount time, which is great! Still there > is > a gap from v6.8 kernel. I think this gap can be a left work, and hope the fix > patch to be upstreamed.
So, v6.8 was buggy in that it allowed a lot higher concurrency than requested. If higher concurrency is desirable, you can just set @max_active to a higher number. Currently, the absolute maximum is 512 (WQ_MAX_ACTIVE) but that number was picked arbitrarily probably more than a decade ago, so if you find higher concurrency useful, we can definitely push up that number. > BTW, the URL of the Link tag is not working. Instead, I suggest this: > > > https://lore.kernel.org/dm-devel/20240410084531.2134621-1-shinichiro.kawas...@wdc.com/ Ah, updated. Thanks. -- tejun
