Re: [RFC][PATCH] sched: Cache aware load-balancing

Chen, Yu C
2025-03-27T08:10:21Z

On 3/26/2025 5:42 PM, Peter Zijlstra wrote:
> On Wed, Mar 26, 2025 at 05:15:24PM +0800, Chen, Yu C wrote:
>> Thanks for running the test. I think hackbenc/schbench would be the good
>> benchmarks to start with. I remember that you and Gautham mentioned that
>> schbench prefers to be aggregated in a single LLC in LPC2021 or 2022. I ran
>> a schbench test using mmtests on a Xeon server which has 4 NUMA nodes. Each
>> node has 80 cores (with SMT disabled). The numa=off option was appended to
>> the boot commandline, so there are 4 "LLCs" within each node.
>
> We really should look at getting the SnC topology even without SnC being
> in use.
>

I agree, unfortunately it seems that with SNC disabled there is no
information exposed to the OS that can be used to divide the large LLC
into smaller pieces.

thanks,
Chenyu

> The sheer size of these LLCs is untenable.