Messages in this thread | | | Subject | Re: [PATCH v3] x86,sched: allow topologies where NUMA nodes share an LLC | From | Dave Hansen <> | Date | Thu, 29 Mar 2018 07:37:29 -0700 |
| |
On 03/29/2018 06:47 AM, Peter Zijlstra wrote: > Further I think Dave argued that we should not change the llc-size, > because while SNC presents a subset of the cache to local CPUs, for > remote data the whole cache is still available, again something some > applications might rely on.
BTW, I may have argued this in the past, but I don't think it's the best thing to do.
If anything, we should optimize for the _users_ of this information: the performance-sensitive ones who are digging up the cache topology. They are also likely to be the most NUMA-affinitized and stay node-local with much of their memory traffic. That would seem to point us in the direction of enumerating two separate, half-sized LLCs "shared" only by the slice when SNC mode is on.
That's what I've argued to the hardware folks lately, at least.
| |