linux-kernel - Re: [PATCH 4/7] sched/fair: Avoid unnecessary balancing of asymmetric capacity groups

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: <20180219145335.GN25235@hirez.programming.kicks-ass.net>
Date:   Mon, 19 Feb 2018 15:53:35 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Morten Rasmussen <morten.rasmussen@....com>
Cc:     mingo@...hat.com, valentin.schneider@....com,
        dietmar.eggemann@....com, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] sched/fair: Avoid unnecessary balancing of
 asymmetric capacity groups

On Mon, Feb 19, 2018 at 03:50:12PM +0100, Peter Zijlstra wrote:
> On Thu, Feb 15, 2018 at 04:20:51PM +0000, Morten Rasmussen wrote:
> > On systems with asymmetric cpu capacities, a skewed load distribution
> > might yield better throughput than balancing load per group capacity.
> > For example, preferring high capacity cpus for compute intensive tasks
> > leaving low capacity cpus idle rather than balancing the number of idle
> > cpus across different cpu types. Instead, let load-balance back off if
> > the busiest group isn't really overloaded.
> 
> I'm sorry. I just can't seem to make sense of that today. What?

Aah, you're saying that is we have 4+4 bit.little and 4 runnable tasks,
we would like them running on our big cluster and leave the small
cluster entirely idle, instead of runnint 2+2.

So what about this DynamicQ nonsense? Or is that so unstructured we
can't really do anything sensible with it?