Re: [PATCH] sched/fair: reduce false sharing on sched_balance_running

[Shrikanth Hegde]

On 4/23/25 23:16, Eric Dumazet wrote:
> rebalance_domains() can attempt to change sched_balance_running
> more than 350,000 times per second on our servers.
>
> If sched_clock_irqtime and sched_balance_running share the
> same cache line, we see a very high cost on hosts with 480 threads
> dealing with many interrupts.
>
> This patch only acquires sched_balance_running when sd->last_balance
> is old enough.
>
> It also moves sched_balance_running into a dedicated cache line on SMP.
>
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Yafang Shao <laoar.shao@xxxxxxxxx>
> Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
> Cc: Josh Don <joshdon@xxxxxxxxxx>
> ---

Hi Eric.

Please check this thread which does the same thing AFAIU.
https://lore.kernel.org/all/20250416035823.1846307-1-tim.c.chen@xxxxxxxxxxxxxxx/

You could also try:
https://lore.kernel.org/all/82baaf6c-f3d9-4c3e-be69-24389eadb18c@xxxxxxxxxxxxx/

Thanks