On 30 November 2018 10:47:45 CET, "Martin Liška" <mli...@suse.cz> wrote: >Hi. > >This patch is a reaction to Jason's commit where he introduced new C++ >attributes. >First I would like to align cold/hot to __builtin_expect, so I adjusted >probability >and made the predictors first match predictors. > >Second I fixed how we consider the predictors in switch statements, so >that >we can correctly predict situation in predict-3. > >Honza is fine with the patch, I'll install it later if there are no >objections. >Survives tests and bootstrap on xc86_64-linux-gnu.
I don't have the sources at hand but in: +/* Branches to hot labels are likely. */ +DEF_PREDICTOR (PRED_HOT_LABEL, "hot label", HITRATE (90), + PRED_FLAG_FIRST_MATCH) + +/* Branches to cold labels are extremely unlikely. */ +DEF_PREDICTOR (PRED_COLD_LABEL, "cold label", HITRATE (90), + PRED_FLAG_FIRST_MATCH) + I would have expected cold labels to have a rather low hitrate, like maybe 2 or 7, not 90 ? Thanks,
