linux-kernel - Re: massive_intr on CFS, BFS, and EDF

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:	Fri, 25 Sep 2009 16:46:17 -0600
From:	"Chris Friesen" <cfriesen@...tel.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Michael Trimarchi <trimarchi@...dalf.sssup.it>,
	sat <takeuchi_satoru@...fujitsu.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Con Kolivas <kernel@...ivas.org>, Ingo Molnar <mingo@...e.hu>,
	Raistlin <raistlin@...ux.it>
Subject: Re: massive_intr on CFS, BFS, and EDF

On 09/25/2009 04:37 PM, Peter Zijlstra wrote:
> On Fri, 2009-09-25 at 15:31 -0600, Chris Friesen wrote:

>> Do you allow oversubscription with EDF?  It would seem so based on these
>> results.  Would it maybe make sense to disallow oversubscription, or
>> make it an option?
> 
> afaiu he doesn't, he simply splits the task's wcet between parent and
> child and (intends?) to feed back on child exit.

How does this work if we have one parent task that forks off a bunch of
kids like massive_intr?  Does each child get half the bandwidth of the
previous child?

> oversubscribing edf isn't in general recommended, iirc u>1 gives
> unbounded latencies with edf.

Right...so would it perhaps be more interesting to try a modified test
where each child's bandwidth is equal and small enough that there is no
oversubscription?

Chris
--
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/