sched/fair: Fix overly small weight for interactive group entities
authorYuyang Du <yuyang.du@intel.com>
Tue, 13 Oct 2015 01:18:22 +0000 (09:18 +0800)
committerIngo Molnar <mingo@kernel.org>
Tue, 20 Oct 2015 08:13:34 +0000 (10:13 +0200)
commitfde7d22e01aa0d252fc5c95fa11f0dac35a4dd59
tree9e5a21c5052af5f7b695a0203f2dca7bdbddd3ea
parent9babcd7929bc8967ae3bb6093f603b93c2f9958f
sched/fair: Fix overly small weight for interactive group entities

Commit:

  9d89c257dfb9 ("sched/fair: Rewrite runnable load and utilization average tracking")

led to an overly small weight for interactive group entities. The bad case
can be easily reproduced when a number of CPU hogs compete for the CPUs
at the same time (thanks to Mike). This is largly because the task group's
load average tracking cross CPUs lags behind the real changes.

To fix this we accelerate the group share distribution process by using
the load.weight of the cfs_rq. This may increase the entire group's
share, but we have to do so to protect the (fragile) interactive
tasks, especially from CPU hogs.

Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1444699103-20272-1-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/sched/fair.c