Hello, Peter.
On Wed, May 03, 2017 at 08:00:28PM +0200, Peter Zijlstra wrote:
> Just FUDGE2 on its own seems to be the best on my system and is a change
> that makes sense (and something Paul recently pointed out as well).
>
> The implementation isn't particularly pretty or fast, but should
> illustrate the idea.
>
> Poking at the whole update_tg_cfs_load() thing only makes it worse after
> that. And while I agree that that code is mind bending; it seems to work
> OK-ish.
>
> Tejun, Vincent, could you guys have a poke?
So, just preliminary testing.
FUDGE: Does cut down the number of wrong picks by about 70% and p99
latency by about half; however, the resulting p99 is still
worse by 5 - 10 times compared to !cgroup case.
FUDGE2: Changes things a lot (load values go wild) but only because
it's missing scale_load_down(). After adding
scale_load_down(), it doesn't do much. For this to work, it
needs to be always propagated, which btw shouldn't be
prohibitively expensive given other operations which are
performed at the same time.
Thanks.
--
tejun
