diff options
Diffstat (limited to 'meta-eas/recipes-kernel/linux/linux-renesas/0080-sched-core-Fix-find_idlest_group-for-fork.patch')
| -rw-r--r-- | meta-eas/recipes-kernel/linux/linux-renesas/0080-sched-core-Fix-find_idlest_group-for-fork.patch | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/meta-eas/recipes-kernel/linux/linux-renesas/0080-sched-core-Fix-find_idlest_group-for-fork.patch b/meta-eas/recipes-kernel/linux/linux-renesas/0080-sched-core-Fix-find_idlest_group-for-fork.patch new file mode 100644 index 0000000..ccf260c --- /dev/null +++ b/meta-eas/recipes-kernel/linux/linux-renesas/0080-sched-core-Fix-find_idlest_group-for-fork.patch @@ -0,0 +1,86 @@ +From 4e4846aafb09473f1ca69fa061e72437b55f78c7 Mon Sep 17 00:00:00 2001 +From: Vincent Guittot <vincent.guittot@linaro.org> +Date: Thu, 8 Dec 2016 17:56:53 +0100 +Subject: [PATCH 80/92] sched/core: Fix find_idlest_group() for fork + +During fork, the utilization of a task is init once the rq has been +selected because the current utilization level of the rq is used to +set the utilization of the fork task. As the task's utilization is +still 0 at this step of the fork sequence, it doesn't make sense to +look for some spare capacity that can fit the task's utilization. +Furthermore, I can see perf regressions for the test: + + hackbench -P -g 1 + +because the least loaded policy is always bypassed and tasks are not +spread during fork. + +With this patch and the fix below, we are back to same performances as +for v4.8. The fix below is only a temporary one used for the test +until a smarter solution is found because we can't simply remove the +test which is useful for others benchmarks + +| @@ -5708,13 +5708,6 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t +| +| avg_cost = this_sd->avg_scan_cost; +| +| - /* +| - * Due to large variance we need a large fuzz factor; hackbench in +| - * particularly is sensitive here. +| - */ +| - if ((avg_idle / 512) < avg_cost) +| - return -1; +| - +| time = local_clock(); +| +| for_each_cpu_wrap(cpu, sched_domain_span(sd), target, wrap) { + +Tested-by: Matt Fleming <matt@codeblueprint.co.uk> +Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> +Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> +Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk> +Acked-by: Morten Rasmussen <morten.rasmussen@arm.com> +Cc: Linus Torvalds <torvalds@linux-foundation.org> +Cc: Peter Zijlstra <peterz@infradead.org> +Cc: Thomas Gleixner <tglx@linutronix.de> +Cc: dietmar.eggemann@arm.com +Cc: kernellwp@gmail.com +Cc: umgwanakikbuti@gmail.com +Cc: yuyang.du@intel.comc +Link: http://lkml.kernel.org/r/1481216215-24651-2-git-send-email-vincent.guittot@linaro.org +Signed-off-by: Ingo Molnar <mingo@kernel.org> +(cherry picked from commit f2e4ac502860c2adcc5ce56e0064fc4bcab90af4) +Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com> +--- + kernel/sched/fair.c | 8 ++++++++ + 1 file changed, 8 insertions(+) + +diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c +index 489f6d3..fea3ca8 100644 +--- a/kernel/sched/fair.c ++++ b/kernel/sched/fair.c +@@ -5809,13 +5809,21 @@ static unsigned long capacity_spare_wake(int cpu, struct task_struct *p) + * utilized systems if we require spare_capacity > task_util(p), + * so we allow for some task stuffing by using + * spare_capacity > task_util(p)/2. ++ * ++ * Spare capacity can't be used for fork because the utilization has ++ * not been set yet, we must first select a rq to compute the initial ++ * utilization. + */ ++ if (sd_flag & SD_BALANCE_FORK) ++ goto skip_spare; ++ + if (this_spare > task_util(p) / 2 && + imbalance*this_spare > 100*most_spare) + return NULL; + else if (most_spare > task_util(p) / 2) + return most_spare_sg; + ++skip_spare: + if (!idlest || 100*this_load < imbalance*min_load) + return NULL; + return idlest; +-- +1.9.1 + |