On Tue, 27 Mar 2018, Dave Hansen wrote: > On 03/27/2018 06:36 AM, Thomas Gleixner wrote: > >> User Time Kernel Time Clock Elapsed > >> Baseline ( 0 GLB PTEs) 803.79 67.77 237.30 > >> w/series (28 GLB PTEs) 807.70 (+0.7%) 68.07 (+0.7%) 238.07 (+0.3%) > >> > >> Without PCIDs, it behaves the way I would expect. > > What's the performance benefit on !PCID systems? And I mean systems which > > actually do not have PCID, not a PCID system with 'nopcid' on the command > > line. > > Do you have something in mind for this? Basically *all* of the servers > that I have access to have PCID because they are newer than ~7 years old. > > That leaves *some* Ivybridge and earlier desktops, Atoms and AMD AMD is not interesting as it's not PTI and uses GLOBAL anyway. > systems. Atoms are going to be the easiest thing to get my hands on, > but I tend to shy away from them for performance work. What I have in mind is that I wonder whether the whole circus is worth it when there is no performance advantage on PCID systems. Thanks, tglx
