Re: [PATCH v4 0/5] kernfs: proposed locking and concurrency improvement

Fox Chen
2021-05-12T08:54:32Z

On Wed, May 12, 2021 at 4:47 PM Fox Chen <foxhlchen@gmail.com> 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

> though there is no mutex problem from the perf report.
> I've put console outputs and perf reports on the attachment for your reference.
>
>
> thanks,
> fox

fox