Re: [PATCH v2 3/4] sched/rt: Split root_domain->rto_count to per-NUMA-node counters

[Tim Chen]

On Fri, 2026-03-20 at 11:24 +0100, Peter Zijlstra wrote:
> On Mon, Jul 21, 2025 at 02:10:25PM +0800, Pan Deng wrote:
> > As a complementary, this patch splits
> > `rto_count` into per-numa-node counters to reduce the contention.
> 
> Right... so Tim, didn't we have similar patches for task_group::load_avg
> or something like that? Whatever did happen there? Can we share common
> infra?

We did talk about introducing per NUMA counter for load_avg. We went with
limiting the update rate of load_avg to not more than once per msec
in commit 1528c661c24b4 to control the cache bounce.

> 
> Also since Tim is sitting on this LLC infrastructure, can you compare
> per-node and per-llc for this stuff? Somehow I'm thinking that a 2
> socket 480 CPU system only has like 2 nodes and while splitting this
> will help some, that might not be excellent.

You mean enhancing the per NUMA counter to per LLC? I think that makes
sense to reduce the LLC cache bounce if there are multiple LLCs per
NUMA node.

Tim

> 
> Please test on both Intel and AMD systems, since AMD has more of these
> LLC things on.
> 
>