On Mon, Jul 24, 2017 at 04:29:05PM -0700, Greg KH wrote: > On Mon, Jul 24, 2017 at 05:44:01PM +0100, Mel Gorman wrote: > > On Thu, Jul 20, 2017 at 10:21:18PM +0100, Mel Gorman wrote: > > > This is a second round of performance-related backports based on low-hanging > > > fruit in the 4.13 merge window based on 4.12.2. > > > > > > As before, these have only been tested on 4.12-stable. While they may > > > merge against older kernels, I have no data on how it behaves and cannot > > > guarantee it's a good idea so I don't recommend it. There will also be > > > some major conflicts that are not trivial to resolve. > > > > > > For most of the tests I conducted, the impact is marginal but patches the > > > first two sets of patches are important for large machines and for uses > > > of nohz_full. The load balancing patch is fairly specific but measurable. > > > The removal of unnecessary IRQ disabling/enabling is borderline in terms of > > > performance but they are trivial patches and avoiding unnecessary expensive > > > operations is always a plus. > > > > > > > With 4.12.3, the patches 1-17 can be dropped. > > Really? Why, what happened in .3 that make the need for those 17 > patches just "go away"? > One of the biggest motivation of the series was to bring in these commits that are now in -stable d5ba2df79bc6ae02927d5465e93eb635809e6db5 sched/topology: Fix overlapping sched_group_mask 3397c1f0371a49f52635c9e60e552ef3c91fa10f sched/topology: Optimize build_group_mask() e64918b4b7c3bac472198d7b59b6092a78092169 sched/topology: Fix building of overlapping sched-groups The series now needs to be rebased on top to deal with minor collisions but once it is, there is only one notable fix left related to scheduler topology -- "sched/topology: Fix overlapping sched_group_capacity" and it is borderline. The bulk of the rest are cleanups, micro-optimisations, simplifications and then documentation so the whole thing is understandable. The rebase is trivial (collisions with comments) but we can also live without them. > > The main commit left over > > that is missing from this series was "sched/topology: Fix overlapping > > sched_group_capacity" which is relatively minor in impact. The rest were > > to bring the schedulers more or less in line so debugging problems in > > 4.12-stable would be easier to compare with mainline and to make the 4.12 > > scheduler easier to understand. > > > > The rest of the series should apply ok on top of 4.12.3 if you'd like to > > pick it up. > > So just patches 18-26? > Yes, that will then be the accounting fixes for nohz_full users, a load balancer fix when some processes are pinned to CPUs and a few minor optimisations that avoid unnecessary disabling of IRQs. Thanks. -- Mel Gorman SUSE Labs