On 03/30/2018 01:32 PM, Thomas Gleixner wrote: > On Fri, 30 Mar 2018, Dave Hansen wrote: > >> On 03/30/2018 05:17 AM, Ingo Molnar wrote: >>> 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. >> >> I did the lseek test on a modern, non-PCID system: >> >> No Global pages (baseline): 6077741 lseeks/sec >> 94 Global pages (this set): 8433111 lseeks/sec >> +2355370 lseeks/sec (+38.8%) > > That's all kernel text, right? What's the result for the case where global > is only set for all user/kernel shared pages? Yes, that's all kernel text (94 global entries). Here's the number with just the entry data/text set global (88 global entries on this system): No Global pages (baseline): 6077741 lseeks/sec 88 Global Pages (kentry ): 7528609 lseeks/sec (+23.9%) 94 Global pages (this set): 8433111 lseeks/sec (+38.8%)
