Subject: Re: [RFC 2/5] sched: Add CPU rate soft caps
From: Mike Galbraith <efault@gmx.de>
To: Con Kolivas <kernel@kolivas.org>
Cc: Peter Williams <pwil3058@bigpond.net.au>,
       Linux Kernel <linux-kernel@vger.kernel.org>,
       Kingsley Cheung <kingsley@aurema.com>, Ingo Molnar <mingo@elte.hu>,
       Rene Herman <rene.herman@keyaccess.nl>
In-Reply-To: <200605262048.53131.kernel@kolivas.org>
References: <20060526042021.2886.4957.sendpatchset@heathwren.pw.nest>
	 <20060526042041.2886.69840.sendpatchset@heathwren.pw.nest>
	 <200605262048.53131.kernel@kolivas.org>
Content-Type: text/plain
Date: Fri, 26 May 2006 13:15:54 +0200
Message-Id: <1148642155.7602.19.camel@homer>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1155
Lines: 26

On Fri, 2006-05-26 at 20:48 +1000, Con Kolivas wrote:
> On Friday 26 May 2006 14:20, Peter Williams wrote:
> > 3. Enforcement of caps is not as strict as it could be in order to
> > reduce the possibility of a task being starved of CPU while holding
> > an important system resource with resultant overall performance
> > degradation.  In effect, all runnable capped tasks will get some amount
> > of CPU access every active/expired swap cycle.  This will be most
> > apparent for small or zero soft caps.
> 
> The array swap happens very frequently if there are nothing but heavily cpu 
> bound tasks, which is not an infrequent workload. I doubt the zero caps are 
> very effective in that environment.

Hmm.  I think that came out kinda back-assward.  You meant "the array
swap happens very frequently _unless_..."  No?

But anyway, I can't think of any reason to hold back an uncontested
resource.

	-Mike

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/