On Thu, Mar 19, 2015 at 04:05:46PM -0700, Linus Torvalds wrote: > On Thu, Mar 19, 2015 at 3:41 PM, Dave Chinner <da...@fromorbit.com> wrote: > > > > My recollection wasn't faulty - I pulled it from an earlier email. > > That said, the original measurement might have been faulty. I ran > > the numbers again on the 3.19 kernel I saved away from the original > > testing. That came up at 235k, which is pretty much the same as > > yesterday's test. The runtime,however, is unchanged from my original > > measurements of 4m54s (pte_hack came in at 5m20s). > > Ok. Good. So the "more than an order of magnitude difference" was > really about measurement differences, not quite as real. Looks like > more a "factor of two" than a factor of 20. > > Did you do the profiles the same way? Because that would explain the > differences in the TLB flush percentages too (the "1.4% from > tlb_invalidate_range()" vs "pretty much everything from migration"). > > The runtime variation does show that there's some *big* subtle > difference for the numa balancing in the exact TNF_NO_GROUP details.
TNF_NO_GROUP affects whether the scheduler tries to group related processes together. Whether migration occurs depends on what node a process is scheduled on. If processes are aggressively grouped inappropriately then it is possible there is a bug that causes the load balancer to move processes off a node (possible migration) with NUMA balancing trying to pull it back (another possible migration). Small bugs there can result in excessive migration. -- Mel Gorman SUSE Labs _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
