linux-kernel - Re: [RFC/PATCH 0/3] sched: allow arch override of cpu power

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]

Date:	Thu, 19 Jun 2008 12:09:45 -0500
From:	Nathan Lynch <ntl@...ox.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org,
	Paul Mackerras <paulus@...ba.org>,
	Anton Blanchard <anton@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [RFC/PATCH 0/3] sched: allow arch override of cpu power

Ingo Molnar wrote:
> 
> * Nathan Lynch <ntl@...ox.com> wrote:
> > So it would be nice to have the scheduler slightly prefer primary 
> > threads on POWER6 machines.  These patches, which allow the 
> > architecture to override the scheduler's CPU "power" calculation, are 
> > one possible approach, but I'm open to others.  Please note: these 
> > seemed to have the desired effect on 2.6.25-rc kernels (2-3% 
> > improvement in a kernbench-like make -j <nr_cores>), but I'm not 
> > seeing this improvement with 2.6.26-rc kernels for some reason I am 
> > still trying to track down.
> 
> ok, i guess that discrepancy has to be tracked down before we can think 
> about these patches - but the principle is OK.

Great.  I'll keep trying to figure out what's going on there.


> One problem is that the whole cpu-power balancing code in sched.c is a 
> bit ... unclear and under-documented. So any change to this area should 
> begin at documenting the basics: what do the units mean exactly, how are 
> they used in balancing and what is the desired effect.
>
> I'd not be surprised if there were a few buglets in this area, SMT is 
> not at the forefront of testing at the moment. There's nothing 
> spectacularly broken in it (i have a HT machine myself), but the 
> concepts have bitrotten a bit. Patches - even if they just add comments 
> - are welcome :-)

Okay, I'll have a look.  Thanks Ingo.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/