linux-kernel - [PATCH 0/1] Improve yield (was: sched: Move SCHED

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Date:   Wed,  7 Jul 2021 14:34:01 +0200
From:   Christian Borntraeger <borntraeger@...ibm.com>
To:     peterz@...radead.org
Cc:     borntraeger@...ibm.com, bristot@...hat.com, bsegall@...gle.com,
        dietmar.eggemann@....com, joshdon@...gle.com,
        juri.lelli@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        linux@...musvillemoes.dk, mgorman@...e.de, mingo@...nel.org,
        rostedt@...dmis.org, valentin.schneider@....com,
        vincent.guittot@...aro.org
Subject: [PATCH 0/1] Improve yield (was: sched: Move SCHED_DEBUG sysctl to debugfs)

I did a reduced testcase and assuming that the reduced testcase has the
same issue, it turns out that a lower sched_migration_cost_ns does not
solve a specific problem, instead it seems to make a different problem
less problematic. In the end the problem seemed to be worse on KVM hosts
(guest changes did also help but much less so). In the end what did help
was to improve the behaviour of yield_to from KVM.
See the patch for more details. The problem seems to be real, my
solution might not be the best one - I am open for better ways to
code things.