linux-kernel - Re: aim7 -30% regression in 2.6.24-rc1

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: <1193733390.3019.210.camel@ymzhang>
Date:	Tue, 30 Oct 2007 16:36:30 +0800
From:	"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: aim7 -30% regression in 2.6.24-rc1

On Tue, 2007-10-30 at 08:26 +0100, Ingo Molnar wrote:
> * Zhang, Yanmin <yanmin_zhang@...ux.intel.com> wrote:
> 
> > sub-bisecting captured patch 
> > 38ad464d410dadceda1563f36bdb0be7fe4c8938(sched: uniform tunings) 
> > caused 20% regression of aim7.
> > 
> > The last 10% should be also related to sched parameters, such like 
> > sysctl_sched_min_granularity.
> 
> ah, interesting. Since you have CONFIG_SCHED_DEBUG enabled, could you 
> please try to figure out what the best value for 
> /proc/sys/kernel_sched_latency, /proc/sys/kernel_sched_nr_latency and 
> /proc/sys/kernel_sched_min_granularity is?
> 
> there's a tuning constraint for kernel_sched_nr_latency: 
> 
> - kernel_sched_nr_latency should always be set to 
>   kernel_sched_latency/kernel_sched_min_granularity. (it's not a free 
>   tunable)
> 
> i suspect a good approach would be to double the value of 
> kernel_sched_latency and kernel_sched_nr_latency in each tuning 
> iteration, while keeping kernel_sched_min_granularity unchanged. That 
> will excercise the tuning values of the 2.6.23 kernel as well.
I followed your idea to test 2.6.24-rc1. The improvement is slow.
When sched_nr_latency=2560 and sched_latency_ns=640000000, the performance
is still about 15% less than 2.6.23.

-yanmin
-
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/