Re: [LKP] Re: [x86/mce] 1de08dccd3: will-it-scale.per_process_ops -14.1% regression

Feng Tang
2020-08-19T03:21:02Z

On Wed, Aug 19, 2020 at 10:23:11AM +0800, Luck, Tony wrote:
> 0000000000019260 D pqr_state
>
> Do you have /sys/fs/resctrl mounted? This variable is read on every context switch.
> If your benchmark does a lot of context switching and this now shares a cache line
> with something different (especially something that is sometimes modified from another
> CPU) that could cause some cache line bouncing.

No, the kernel doesn't has /sys/fs/resctrl mounted.

And the test case is not context switch intensive. It just forks a task
for each CPU which loops running malloc/free and counts the number of
complted operations for 300 seconds.

Thanks,
Feng