linux-kernel - Re: High priority tasks break SMP balancer?

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 for Android: free password hash cracker in your pocket

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

Date:	Fri, 16 Nov 2007 07:07:00 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Micah Dowty <micah@...are.com>
Cc:	Christoph Lameter <clameter@....com>,
	Kyle Moffett <mrmacman_g4@....com>,
	Cyrus Massoumi <cyrusm@....net>,
	LKML Kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...l.org>, Mike Galbraith <efault@....de>,
	Paul Menage <menage@...gle.com>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Peter Williams <pwil3058@...pond.net.au>
Subject: Re: High priority tasks break SMP balancer?


* Micah Dowty <micah@...are.com> wrote:

> > I am a bit at a loss as to how this could relate to the patch. This 
> > looks like a load balance logic issue that causes the load 
> > calculation to go wrong?
> 
> My best guess is that this has something to do with the timing with 
> which we sample the CPU's instantaneous load when calculating the load 
> averages.. but I still understand only the basics of the scheduler and 
> SMP balancer. All I really know for sure at this point regarding your 
> patch is that git-bisect found it for me.

hm, your code uses timeouts for this, right? The CPU load average that 
is used for SMP load balancing is sampled from the scheduler tick - and 
has been sampled from the scheduler tick for eons. v2.6.23 defaulted to 
a different method but v2.6.24 samples it from the tick again. So my 
guess is, your testcode behave similarly on 2.6.22 too, correct?

	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/