Messages in this thread | | | Subject | Re: [PATCH v4 00/12] sched: Avoid unnecessary migrations within SMT domains | From | Tim Chen <> | Date | Mon, 01 May 2023 11:30:21 -0700 |
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On Sat, 2023-04-29 at 17:32 +0200, Peter Zijlstra wrote: > On Thu, Apr 06, 2023 at 01:31:36PM -0700, Ricardo Neri wrote: > > Hi, > > > > This is v4 of this series. Previous versions can be found here [1], [2], > > and here [3]. To avoid duplication, I do not include the cover letter of > > the original submission. You can read it in [1]. > > > > This patchset applies cleanly on today's master branch of the tip tree. > > > > Changes since v3: > > > > Nobody liked the proposed changes to the setting of prefer_sibling. > > Instead, I tweaked the solution that Dietmar proposed. Now the busiest > > group, not the local group, determines the setting of prefer_sibling. > > > > Vincent suggested improvements to the logic to decide whether to follow > > asym_packing priorities. Peter suggested to wrap that in a helper function. > > I added sched_use_asym_prio(). > > > > Ionela found that removing SD_ASYM_PACKING from the SMT domain in x86 > > rendered sd_asym_packing NULL in SMT cores. Now highest_flag_domain() > > does not assume that all child domains have the requested flag. > > > > Tim found that asym_active_balance() needs to also check for the idle > > states of the SMT siblings of lb_env::dst_cpu. I added such check. > > > > I wrongly assumed that asym_packing could only be used when the busiest > > group had exactly one busy CPU. This broke asym_packing balancing at the > > DIE domain. I limited this check to balances between cores at the MC > > level. > > > > As per suggestion from Dietmar, I removed sched_asym_smt_can_pull_tasks() > > and placed its logic in sched_asym(). Also, sched_asym() uses > > sched_smt_active() to skip checks when not needed. > > > > I also added a patch from Chen Yu to enable asym_packing balancing in > > Meteor Lake, which has CPUs of different maximum frequency in more than > > one die. > > Is the actual topology of Meteor Lake already public? This patch made me > wonder if we need SCHED_CLUSTER topology in the hybrid_topology thing, > but I can't remember (one of the raisins why the endless calls are such > a frigging waste of time) and I can't seem to find the answer using > Google either.
There are a bunch of fixes that are needed for SCHED_CLUSTER to work properly on hybrid_topology. I'll clean them up and post them on top of Ricardo's current patch set this week.
Tim
> > > Hopefully, these patches are in sufficiently good shape to be merged?
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