From: Qais Yousef <email@example.com> To: Ingo Molnar <firstname.lastname@example.org>, Peter Zijlstra <email@example.com>, Steven Rostedt <firstname.lastname@example.org>, Pavan Kondeti <email@example.com>, Dietmar Eggemann <firstname.lastname@example.org> Cc: Juri Lelli <email@example.com>, Vincent Guittot <firstname.lastname@example.org>, Ben Segall <email@example.com>, Mel Gorman <firstname.lastname@example.org>, email@example.com, Qais Yousef <firstname.lastname@example.org> Subject: [PATCH 0/3] RT Capacity Awareness Improvements Date: Fri, 14 Feb 2020 16:39:46 +0000 [thread overview] Message-ID: <email@example.com> (raw) Pavan has pointed out an oversight in the first implementation where we don't fallback to another unfitting CPU if we are already running on unfitting one. This also stirred discussion around handling downmigration from fitting to unfitting CPU. https://firstname.lastname@example.org/ Patch 1 adds the missing fallback when a fitting CPU wasn't found, reported by Pavan. Patch 2 allows downmigration in the pull case and marks the CPU as overloaded as suggested by Steve. Patch 3 fixes the condition in select_task_rq_rt() in case the new_cpu and the task priorities are the *same*. The series is based on Linus/master v5.6-rc1. I ran the following test cases, the results of which can be found in  Each test was run 3 times to demonstrate repeatability of the result. The tests were ran on Juno-r2, which has 6 CPUs. CPUs [0, 3-5] are Littles and CPUs [1-2] are Bigs. By default RT tasks are boosted to max capacity, so no work was done to modify that. ie: rt_task->uclamp_min = 1024 for all running tests. 1. 6 RT Tasks * 2 Tasks always end up on the big cores * The rest end up on the little cores with migration among them happening (it didn't before) 2. 2 RT Tasks * We can see they always end up on the 2 big cores 3. 4 RT Tasks * Results similar to 1 4. 4 RT Tasks affined to little cores * The tasks run on the little cores with some migration as expected  https://gist.github.com/qais-yousef/bb99bdd912628489408a5edae33f85e1 Qais Yousef (3): sched/rt: cpupri_find: implement fallback mechanism for !fit case sched/rt: allow pulling unfitting task sched/rt: fix pushing unfit tasks to a better CPU kernel/sched/cpupri.c | 157 +++++++++++++++++++++++++++--------------- kernel/sched/rt.c | 50 ++++++++++---- 2 files changed, 139 insertions(+), 68 deletions(-) -- 2.17.1
next reply other threads:[~2020-02-14 16:40 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-14 16:39 Qais Yousef [this message] 2020-02-14 16:39 ` [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case Qais Yousef 2020-02-17 17:07 ` Valentin Schneider 2020-02-17 23:34 ` Qais Yousef 2020-02-18 10:01 ` Valentin Schneider 2020-02-17 19:09 ` Dietmar Eggemann 2020-02-17 23:45 ` Qais Yousef 2020-02-18 9:53 ` Dietmar Eggemann 2020-02-18 17:28 ` Qais Yousef 2020-02-18 16:46 ` Steven Rostedt 2020-02-18 17:27 ` Qais Yousef 2020-02-18 18:03 ` Steven Rostedt 2020-02-18 18:52 ` Qais Yousef 2020-02-14 16:39 ` [PATCH 2/3] sched/rt: allow pulling unfitting task Qais Yousef 2020-02-17 9:10 ` Pavan Kondeti 2020-02-17 11:20 ` Qais Yousef 2020-02-19 13:43 ` Qais Yousef 2020-02-21 8:07 ` Pavan Kondeti 2020-02-21 11:08 ` Qais Yousef 2020-02-14 16:39 ` [PATCH 3/3] sched/rt: fix pushing unfit tasks to a better CPU Qais Yousef 2020-02-17 9:23 ` Pavan Kondeti 2020-02-17 13:53 ` Qais Yousef 2020-02-18 4:16 ` Pavan Kondeti 2020-02-18 17:47 ` Qais Yousef 2020-02-19 2:46 ` Pavan Kondeti 2020-02-19 10:46 ` Qais Yousef 2020-02-19 14:02 ` Qais Yousef 2020-02-21 8:15 ` Pavan Kondeti 2020-02-21 11:12 ` Qais Yousef
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