forked from luck/tmp_suning_uos_patched
67d4f6ff2f
While staring at build_sched_domains(), I realized that get_group()
does several duplicate (thus useless) writes.
If you take the Arm Juno r0 (LITTLEs = [0, 3, 4, 5], bigs = [1, 2]), the
sched_group build flow would look like this:
('MC[cpu]->sg' means 'per_cpu_ptr(&tl->data->sg, cpu)' with 'tl == MC')
build_sched_groups(MC[CPU0]->sd, CPU0)
get_group(0) -> MC[CPU0]->sg
get_group(3) -> MC[CPU3]->sg
get_group(4) -> MC[CPU4]->sg
get_group(5) -> MC[CPU5]->sg
build_sched_groups(DIE[CPU0]->sd, CPU0)
get_group(0) -> DIE[CPU0]->sg
get_group(1) -> DIE[CPU1]->sg <=================+
|
build_sched_groups(MC[CPU1]->sd, CPU1) |
get_group(1) -> MC[CPU1]->sg |
get_group(2) -> MC[CPU2]->sg |
|
build_sched_groups(DIE[CPU1]->sd, CPU1) ^
get_group(1) -> DIE[CPU1]->sg } We've set up these two up here!
get_group(3) -> DIE[CPU0]->sg }
From this point on, we will only use sched_groups that have been
previously visited & initialized. The only new operation will
be which group pointer we affect to sd->groups.
On the Juno r0 we get 32 get_group() calls, every single one of them
writing to a sched_group->cpumask. However, all of the data structures
we need are set up after 8 visits (see above).
Return early from get_group() if we've already visited (and thus
initialized) the sched_group we're looking at. Overlapping domains
are not affected as they do not use build_sched_groups().
Tested on a Juno and a 2 * (Xeon E5-2690) system.
( FWIW I initially checked the refs for both sg && sg->sgc, but figured if
they weren't both 0 or > 1 then something must have gone wrong, so I
threw in a WARN_ON(). )
No change in functionality intended.
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
||
|---|---|---|
| .. | ||
| autogroup.c | ||
| autogroup.h | ||
| clock.c | ||
| completion.c | ||
| core.c | ||
| cpuacct.c | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpufreq_schedutil.c | ||
| cpufreq.c | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| fair.c | ||
| features.h | ||
| idle.c | ||
| isolation.c | ||
| loadavg.c | ||
| Makefile | ||
| membarrier.c | ||
| pelt.c | ||
| pelt.h | ||
| psi.c | ||
| rt.c | ||
| sched-pelt.h | ||
| sched.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| swait.c | ||
| topology.c | ||
| wait_bit.c | ||
| wait.c | ||