On Wed, Jan 23, 2019 at 02:19:24PM +0000, Patrick Bellasi wrote:

On 23-Jan 10:22, Peter Zijlstra wrote:

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On Tue, Jan 22, 2019 at 03:41:29PM +0000, Patrick Bellasi wrote:

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On 22-Jan 16:13, Peter Zijlstra wrote:

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On Tue, Jan 22, 2019 at 02:43:29PM +0000, Patrick Bellasi wrote:

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Do you think that could be acceptable?

Think so, it's a sysctl poke, 'nobody' ever does that.

Cool, so... I'll keep lazy update for system default.

Ah, I think I misunderstood. I meant to say that since nobody ever pokes
at sysctl's it doesn't matter if its a little more expensive and iterate
everything.

Here I was more worried about the code complexity/overhead... for
something actually not very used/useful.

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Also; if you always keep everything up-to-date, you can avoid doing that
duplicate accounting.

To update everything we will have to walk all the CPUs and update all
the RUNNABLE tasks currently enqueued, which are either RT or CFS.

That's way more expensive both in code and time then what we do for
cgroups, where at least we have a limited scope since the cgroup
already provides a (usually limited) list of tasks to consider.

Do you think it's really worth to have ?

Dunno; the whole double bucket thing seems a bit weird to me; but maybe
it will all look better without the mapping stuff.