linux-kernel - Re: [PATCH 4/4] sched,fair: remove effective

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170626161250.GD4941@worktop>
Date:   Mon, 26 Jun 2017 18:12:50 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Rik van Riel <riel@...hat.com>
Cc:     linux-kernel@...r.kernel.org, jhladky@...hat.com, mingo@...nel.org,
        mgorman@...e.de
Subject: Re: [PATCH 4/4] sched,fair: remove effective_load

On Mon, Jun 26, 2017 at 11:20:54AM -0400, Rik van Riel wrote:

> Oh, indeed.  I guess in wake_affine() we should test
> whether the CPUs are in the same NUMA node, rather than
> doing cpus_share_cache() ?

Well, since select_idle_sibling() is on LLC; the early test on
cpus_share_cache(prev,this) seems to actually make sense.

But then cutting out all the other bits seems wrong. Not in the least
because !NUMA_BALACING should also still keep working.

> Or, alternatively, have an update_numa_stats() variant
> for numa_wake_affine() that works on the LLC level?

I think we want to retain the existing behaviour for everything
larger than LLC, and when NUMA_BALANCING, smaller than NUMA.

Also note that your use of task_h_load() in the new numa thing suffers
from exactly the problem effective_load() is trying to solve.