Messages in this thread | | | From | Tony Luck <> | Date | Wed, 5 Jul 2017 10:59:50 -0700 | Subject | Re: [PATCH 08/21] x86/intel_rdt/cqm: Add RMID(Resource monitoring ID) management |
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> In case that a RMID was never used on a particular package, the state check > forces an IPI on all packages unconditionally. That's suboptimal at least. > > We know on which package a given RMID was used, so we could restrict the > checks to exactly these packages, but I'm not sure it's worth the > trouble. We might at least document that and explain why this is > implemented in that way.
We only allocate RMIDs when a user makes a directory. I don't think we should consider options that slow down context switch in order to keep track of which packages were used just to make mkdir(2) a bit faster in the case where we need to check the limbo list.
We could make the check of the limbo list less costly by using a bitmask to keep track of which packages have already found that the llc_occupancy is below the threshold. But I'd question whether the extra complexity in the code was really worth it.
-Tony [on vacation - responses will be slow]
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