Messages in this thread | | | Date | Fri, 7 Nov 2014 13:20:52 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 10/11] perf/x86/intel: Perform rotation on Intel CQM RMIDs |
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On Thu, Nov 06, 2014 at 12:23:21PM +0000, Matt Fleming wrote: > +/* > + * If we fail to assign a new RMID for intel_cqm_rotation_rmid because > + * cachelines are still tagged with RMIDs in limbo, we progressively > + * increment the threshold until we find an RMID in limbo with <= > + * __intel_cqm_threshold lines tagged. This is designed to mitigate the > + * problem where cachelines tagged with an RMID are not steadily being > + * evicted. > + * > + * On successful rotations we decrease the threshold back towards zero. > + * > + * __intel_cqm_max_threshold provides an upper bound on the threshold, > + * and is measured in bytes because it's exposed to userland. > + */ > +static unsigned int __intel_cqm_threshold; > +static unsigned int __intel_cqm_max_threshold = -1;
Should we initialize that to a finite value? Surely results are absolute crap if we do indeed reach that max?
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