* Ingo Molnar <mingo@xxxxxxxxxx> wrote: > > No Global pages (baseline): 186.951 seconds time elapsed ( +- 0.35% ) > > 28 Global pages (this set): 185.756 seconds time elapsed ( +- 0.09% ) > > -1.195 seconds (-0.64%) > > > > Lower is better here, obviously. > > > > I also re-checked everything using will-it-scale's llseek1 test[2] which > > is basically a microbenchmark of a halfway reasonable syscall. Higher > > here is better. > > > > No Global pages (baseline): 15783951 lseeks/sec > > 28 Global pages (this set): 16054688 lseeks/sec > > +270737 lseeks/sec (+1.71%) > > > > So, both the kernel compile and the microbenchmark got measurably faster. > > Ok, cool, this is much better! > > Mind re-sending the patch-set against latest -tip so it can be merged? > > At this point !PCID Intel hardware is not a primary concern, if something bad > happens on them with global pages we can quirk global pages off on them in some > way, or so. BTW., the expectation on !PCID Intel hardware would be for global pages to help even more than the 0.6% and 1.7% you measured on PCID hardware: PCID already _reduces_ the cost of TLB flushes - so if there's not even PCID then global pages should help even more. In theory at least. Would still be nice to measure it. Thanks, Ingo
