[PATCH v2 0/2] ipc/msg: mitigate the lock contention in ipc/msg

Jiebin Sun
2022-09-05T11:16:20Z

Hi,

Here are two patches to mitigate the lock contention in ipc/msg.

The 1st patch is to add the new function percpu_counter_add_local if
only update the local counter without aggregating to global counter.

The 2nd patch is to use percpu_counter_add_local instead of atomic
updating in do_msgsnd and do_msgrcv every time. It will always do
sum when the syscall msgctl_info. So there is no need to do global
adding in percpu_counter_add_batch. We add percpu_counter_add_local
to resolve the above issue. The sum operation in msgctl_info is
infrequent and the additional cost is much less compared to the
performance gain in do_msgsnd and do_msgrcv.

Changes in v2:
1. Separate the original patch into two patches.
2. Add error handling for percpu_counter_init.

The performance gain increases as the threads of workload become larger.
Performance gain: 3.38x

CPU: ICX 8380 x 2 sockets
Core number: 40 x 2 physical cores
Benchmark: pts/stress-ng-1.4.0
-- system v message passing (160 threads)

Regards
Jiebin