Re: [PATCH v3 1/4] sched/fair: add SD_CLUSTER in comments

Valentin Schneider
2024-02-02T14:27:38Z

Subject nit: the prefix should be sched/topology

On 01/02/24 19:54, alexs@kernel.org wrote:
> From: Alex Shi <alexs@kernel.org>
>
> The description of SD_CLUSTER is missing. Add it.
>
> Signed-off-by: Alex Shi <alexs@kernel.org>
> To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> To: Valentin Schneider <vschneid@redhat.com>
> To: Vincent Guittot <vincent.guittot@linaro.org>
> To: Juri Lelli <juri.lelli@redhat.com>
> To: Peter Zijlstra <peterz@infradead.org>
> To: Ingo Molnar <mingo@redhat.com>
> ---
> kernel/sched/topology.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 10d1391e7416..8b45f16a1890 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -1554,6 +1554,7 @@ static struct cpumask ***sched_domains_numa_masks;
> * function:
> *
> * SD_SHARE_CPUCAPACITY - describes SMT topologies
> + * SD_CLUSTER - describes CPU Cluster topologies

So I know this is the naming we've gone for the "Cluster" naming, but this
comment isn't really explaining anything.

include/linux/sched/sd_flags.h has a bit more info already:
* Domain members share CPU cluster (LLC tags or L2 cache)

I had to go through a bit of git history to remember what the CLUSTER thing
was about, how about this:

* SD_CLUSTER - describes shared shared caches, cache tags or busses
* SD_SHARE_PKG_RESOURCES - describes shared LLC cache

And looking at this it would make sense to:
rename SD_CLUSTER into SD_SHARE_PKG_RESOURCES
rename SD_SHARE_PKG_RESOURCES into SD_SHARE_LLC
but that's another topic...

> * SD_SHARE_PKG_RESOURCES - describes shared caches
> * SD_NUMA - describes NUMA topologies
> *
> --
> 2.43.0