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.