Re: [PATCH v5 2/2] ipc/msg: mitigate the lock contention with percpu counter

[Tim Chen]

On Sat, 2022-09-10 at 04:36 +0800, Jiebin Sun wrote:
> The msg_bytes and msg_hdrs atomic counters are frequently
> updated when IPC msg queue is in heavy use, causing heavy
> cache bounce and overhead. Change them to percpu_counter
> greatly improve the performance. Since there is one percpu
> struct per namespace, additional memory cost is minimal.
> Reading of the count done in msgctl call, which is infrequent.
> So the need to sum up the counts in each CPU is infrequent.
> 
> Apply the patch and test the pts/stress-ng-1.4.0
> -- system v message passing (160 threads).
> 
> Score gain: 3.99x
> 
> 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)

Reviewed-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>

> 
> Signed-off-by: Jiebin Sun <jiebin.sun@xxxxxxxxx>
> ---
>