linux-kernel - Re: [PATCH 09/10] sched, fair: Fix the sd_parent

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:	Tue, 27 Aug 2013 02:05:06 -0700
From:	Paul Turner <pjt@...gle.com>
To:	Rik van Riel <riel@...riel.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Mike Galbraith <efault@....de>, Alex Shi <alex.shi@...el.com>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Namhyung Kim <namhyung@...nel.org>,
	Lei Wen <leiwen@...vell.com>, Joonsoo Kim <js1304@...il.com>
Subject: Re: [PATCH 09/10] sched, fair: Fix the sd_parent_degenerate() code

On Mon, Aug 26, 2013 at 2:49 PM, Rik van Riel <riel@...riel.com> wrote:
> On 08/26/2013 08:09 AM, Peter Zijlstra wrote:
>> On Sat, Aug 24, 2013 at 03:45:57AM -0700, Paul Turner wrote:
>>>> @@ -5157,6 +5158,13 @@ cpu_attach_domain(struct sched_domain *s
>>>>                         tmp->parent = parent->parent;
>>>>                         if (parent->parent)
>>>>                                 parent->parent->child = tmp;
>>>> +                       /*
>>>> +                        * Transfer SD_PREFER_SIBLING down in case of a
>>>> +                        * degenerate parent; the spans match for this
>>>> +                        * so the property transfers.
>>>> +                        */
>>>> +                       if (parent->flags & SD_PREFER_SIBLING)
>>>> +                               tmp->flags |= SD_PREFER_SIBLING;
>>>>                         destroy_sched_domain(parent, cpu);
>>>>                 } else
>>>>                         tmp = tmp->parent;
>>>>
>>>
>>> Reviewed-by: Paul Turner <pjt@...gle.com>
>>
>> BTW, did that comment make sense to you or would you suggest something
>> different? I had/am having a hard time with that comment. Somehow it
>> leaves me wanting. I know I understand the issue now, but I'll doubt the
>> comment will suffice in a years time :/
>
> The comment made sense to me :)

It makes sense once you read the code.  That we push down is somehow
counter intuitive in the reading.

>
> --
> All rights reversed.
--
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/