From: Vincent Guittot <vincent.guittot@linaro.org>
To: linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org
Cc: pauld@redhat.com, valentin.schneider@arm.com,
srikar@linux.vnet.ibm.com, quentin.perret@arm.com,
dietmar.eggemann@arm.com, Morten.Rasmussen@arm.com,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH v2 0/8] sched/fair: rework the CFS load balance
Date: Thu, 1 Aug 2019 16:40:16 +0200 [thread overview]
Message-ID: <1564670424-26023-1-git-send-email-vincent.guittot@linaro.org> (raw)
Several wrong task placement have been raised with the current load
balance algorithm but their fixes are not always straight forward and
end up with using biased values to force migrations. A cleanup and rework
of the load balance will help to handle such UCs and enable to fine grain
the behavior of the scheduler for other cases.
Patch 1 has already been sent separatly and only consolidate asym policy
in one place and help the review of the changes in load_balance.
Patch 2 renames the sum of h_nr_running in stats.
Patch 3 removes meaningless imbalance computation to make review of
patch 4 easier.
Patch 4 reworks load_balance algorithm and fixes some wrong task placement
but try to stay conservative.
Patch 5 add the sum of nr_running to monitor non cfs tasks and take that
into account when pulling tasks.
Patch 6 replaces runnable_load by load now that the metrics is only used
when overloaded.
Patch 7 improves the spread of tasks at the 1st scheduling level.
Patch 8 uses utilization instead of load in all steps of misfit task
path.
Some benchmarks results based on 8 iterations of each tests:
- small arm64 dual quad cores system
tip/sched/core w/ this patchset improvement
schedpipe 54981 +/-0.36% 55459 +/-0.31% (+0.97%)
hackbench
1 groups 0.906 +/-2.34% 0.906 +/-2.88% (+0.06%)
- large arm64 2 nodes / 224 cores system
tip/sched/core w/ this patchset improvement
schedpipe 125665 +/-0.61% 125455 +/-0.62% (-0.17%)
hackbench -l (256000/#grp) -g #grp
1 groups 15.263 +/-3.53% 13.776 +/-3.30% (+9.74%)
4 groups 5.852 +/-0.57% 5.340 +/-8.03% (+8.75%)
16 groups 3.097 +/-1.08% 3.246 +/-0.97% (-4.81%)
32 groups 2.882 +/-1.04% 2.845 +/-1.02% (+1.29%)
64 groups 2.809 +/-1.30% 2.712 +/-1.17% (+3.45%)
128 groups 3.129 +/-9.74% 2.813 +/-6.22% (+9.11%)
256 groups 3.559 +/-11.07% 3.020 +/-1.75% (+15.15%)
dbench
1 groups 330.897 +/-0.27% 330.612 +/-0.77% (-0.09%)
4 groups 932.922 +/-0.54% 941.817 +/*1.10% (+0.95%)
16 groups 1932.346 +/-1.37% 1962.944 +/-0.62% (+1.58%)
32 groups 2251.079 +/-7.93% 2418.531 +/-0.69% (+7.44%)
64 groups 2104.114 +/-9.67% 2348.698 +/-11.24% (+11.62%)
128 groups 2093.756 +/-7.26% 2278.156 +/-9.74% (+8.81%)
256 groups 1216.736 +/-2.46% 1665.774 +/-4.68% (+36.91%)
tip/sched/core sha1:
a1dc0446d649 ('sched/core: Silence a warning in sched_init()')
Changes since v1:
- fixed some bugs
- Used switch case
- Renamed env->src_grp_type to env->balance_type
- split patches in smaller ones
- added comments
Vincent Guittot (8):
sched/fair: clean up asym packing
sched/fair: rename sum_nr_running to sum_h_nr_running
sched/fair: remove meaningless imbalance calculation
sched/fair: rework load_balance
sched/fair: use rq->nr_running when balancing load
sched/fair: use load instead of runnable load
sched/fair: evenly spread tasks when not overloaded
sched/fair: use utilization to select misfit task
kernel/sched/fair.c | 769 ++++++++++++++++++++++++++++-----------------------
kernel/sched/sched.h | 2 +-
2 files changed, 419 insertions(+), 352 deletions(-)
--
2.7.4
next reply other threads:[~2019-08-01 14:40 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 14:40 Vincent Guittot [this message]
2019-08-01 14:40 ` [PATCH v2 1/8] sched/fair: clean up asym packing Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 2/8] sched/fair: rename sum_nr_running to sum_h_nr_running Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 3/8] sched/fair: remove meaningless imbalance calculation Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 4/8] sched/fair: rework load_balance Vincent Guittot
2019-08-05 17:07 ` Valentin Schneider
2019-08-26 9:26 ` Vincent Guittot
2019-08-28 10:25 ` Valentin Schneider
2019-08-06 15:56 ` Peter Zijlstra
2019-08-26 9:31 ` Vincent Guittot
2019-08-06 17:17 ` Valentin Schneider
2019-08-07 11:16 ` Valentin Schneider
2019-08-26 10:11 ` Vincent Guittot
2019-08-28 14:19 ` Valentin Schneider
2019-08-29 14:26 ` Vincent Guittot
2019-08-30 14:33 ` Valentin Schneider
2019-08-01 14:40 ` [PATCH v2 5/8] sched/fair: use rq->nr_running when balancing load Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 6/8] sched/fair: use load instead of runnable load Vincent Guittot
2019-08-06 16:07 ` Peter Zijlstra
2019-08-26 15:45 ` Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 7/8] sched/fair: evenly spread tasks when not overloaded Vincent Guittot
2019-08-01 14:40 ` [PATCH v2 8/8] sched/fair: use utilization to select misfit task Vincent Guittot
2019-08-01 16:27 ` Valentin Schneider
2019-08-02 8:29 ` Vincent Guittot
2019-08-02 10:49 ` Valentin Schneider
2019-08-02 12:56 ` [PATCH v3] " Vincent Guittot
2019-08-02 14:27 ` Valentin Schneider
2019-08-05 11:01 ` Valentin Schneider
2019-08-29 19:23 ` [PATCH v2 0/8] sched/fair: rework the CFS load balance Phil Auld
2019-08-30 6:46 ` Vincent Guittot
[not found] ` <20190809052124.13016-1-hdanton@sina.com>
2019-09-02 13:07 ` [PATCH v2 5/8] sched/fair: use rq->nr_running when balancing load Vincent Guittot
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