Hi Ian On Thu, May 13, 2021 at 10:10 PM Ian Kent <raven@xxxxxxxxxx> wrote: > > On Wed, 2021-05-12 at 16:54 +0800, Fox Chen wrote: > > On Wed, May 12, 2021 at 4:47 PM Fox Chen <foxhlchen@xxxxxxxxx> wrote: > > > > > > Hi, > > > > > > I ran it on my benchmark ( > > > https://github.com/foxhlchen/sysfs_benchmark). > > > > > > machine: aws c5 (Intel Xeon with 96 logical cores) > > > kernel: v5.12 > > > benchmark: create 96 threads and bind them to each core then run > > > open+read+close on a sysfs file simultaneously for 1000 times. > > > result: > > > Without the patchset, an open+read+close operation takes 550-570 > > > us, > > > perf shows significant time(>40%) spending on mutex_lock. > > > After applying it, it takes 410-440 us for that operation and perf > > > shows only ~4% time on mutex_lock. > > > > > > It's weird, I don't see a huge performance boost compared to v2, > > > even > > > > I meant I don't see a huge performance boost here and it's way worse > > than v2. > > IIRC, for v2 fastest one only takes 40us > > Thanks Fox, > > I'll have a look at those reports but this is puzzling. > > Perhaps the added overhead of the check if an update is > needed is taking more than expected and more than just > taking the lock and being done with it. Then there's > the v2 series ... I'll see if I can dig out your reports > on those too. Apologies, I was mistaken, it's compared to V3, not V2. The previous benchmark report is here. https://lore.kernel.org/linux-fsdevel/CAC2o3DKNc=sL2n8291Dpiyb0bRHaX=nd33ogvO_LkJqpBj-YmA@xxxxxxxxxxxxxx/ > > > > > > > though there is no mutex problem from the perf report. > > > I've put console outputs and perf reports on the attachment for > > > your reference. > > Yep, thanks. > Ian > thanks, fox
