linux-kernel - Re: [PATCH 2/2] nohz: make nohz

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: <551EE81C.3050605@ezchip.com>
Date:	Fri, 3 Apr 2015 15:21:00 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	Mike Galbraith <umgwanakikbuti@...il.com>
CC:	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] nohz: make nohz_full imply isolcpus

On 04/03/2015 02:08 PM, Mike Galbraith wrote:
> On Fri, 2015-04-03 at 12:24 -0400, cmetcalf@...hip.com wrote:
>> From: Chris Metcalf <cmetcalf@...hip.com>
>>
>> It's not clear that nohz_full is useful without isolcpus also
>> set, since otherwise the scheduler has to run periodically to
>> try to determine whether to steal work from other cores.
>>
>> Signed-off-by: Chris Metcalf <cmetcalf@...hip.com>
> Ack!  nohz_full= as currently defined makes zero sense when the cpu
> set (which should be spelled cpuset) remains connected to the
> scheduler.  Perturbation of tasks to PREVENT cpu domination is what
> the scheduler does for a living.  Sprinkling microsecond savers all
> over the kernel is pretty silly if you don't shut down the mother lode
> of perturbation.

Sounds like a thumbs up for this patch, then?  :-)

-- 
Chris Metcalf, EZChip Semiconductor
http://www.ezchip.com

--
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/