Messages in this thread | | | Date | Tue, 14 Jan 2014 09:58:26 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 0/4] x86: Add Cache QoS Monitoring (CQM) support |
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On 01/12/2014 11:55 PM, Peter Zijlstra wrote: > > The problem is, since there's a limited number of RMIDs we have to > rotate at some point, but since changing RMIDs is nondeterministic we > can't. >
This is fundamentally the crux here. RMIDs are quite expensive for the hardware to implement, so they are limited - but recycling them is *very* expensive because you literally have to touch every line in the cache.
-hpa
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