On Mon, 2014-01-06 at 22:26 +0100, Peter Zijlstra wrote: > On Mon, Jan 06, 2014 at 08:10:45PM +0000, Waskiewicz Jr, Peter P wrote: > > There is one per logical CPU. However, in the current generation, they > > report on the usage of the same L3 cache. But the CPU takes care of the > > resolution of which MSR write and read comes from the logical CPU, so > > software doesn't need to lock access to it from different CPUs. > > What are the rules of RMIDs, I can't seem to find that in the SDM and I > think you're tagging cachelines with them. Which would mean that in > order to (re) use them you need a complete cache (L3) wipe. The cacheline is tagged internally with the RMID as part of the waymask for the thread in the core. > Without a wipe you keep having stale entries of the former user and no > clear indication on when your numbers are any good. That can happen, yes. If you have leftover cache data from a process that died that hasn't been evicted yet and it's assigned to the RMID you're using, you will see its included cache occupancy to the overall numbers. > Also, is there any sane way of shooting down the entire L3? That is a question I'd punt to hpa, but I'll ask him. Looking around though, a WBINVD would certainly nuke things, but would hurt performance. We could get creative with INVPCID as a process dies. Let me ask him though and see if there's a good way to tidy up. -PJ -- PJ Waskiewicz Open Source Technology Center peter.p.waskiewicz.jr@xxxxxxxxx Intel Corp. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
