Messages in this thread |  | | Date | Thu, 20 Sep 2018 16:11:15 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH V5 5/6] x86/intel_rdt: Use perf infrastructure for measurements |
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On Wed, Sep 19, 2018 at 10:29:10AM -0700, Reinette Chatre wrote: > +static int measure_l3_residency(void *_plr) > +{
> + counts.miss_after -= counts.miss_before; > + if (boot_cpu_data.x86_model == INTEL_FAM6_BROADWELL_X) { > + /* > + * On BDW references and misses are counted, need to adjust. > + * Sometimes the "hits" counter is a bit more than the > + * references, for example, x references but x + 1 hits. > + * To not report invalid hit values in this case we treat > + * that as misses equal to references. > + */ > + /* First compute the number of cache references measured */ > + counts.hits_after -= counts.hits_before;
> + /* Next convert references to cache hits */ > + counts.hits_after -= counts.miss_after > counts.hits_after ? > + counts.hits_after : counts.miss_after;
Maybe: counts.hits_after -= min(counts.hits_after, counts.miss_after);
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