linux-kernel - Re: [PATCH] sched: correct how RT task is picked

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: <BANLkTikOecxhb8pZfAd19FLrPAPY4zacDQ@mail.gmail.com>
Date:	Wed, 11 May 2011 21:44:04 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	Yong Zhang <yong.zhang0@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Galbraith <efault@....de>
Subject: Re: [PATCH] sched: correct how RT task is picked

On Wed, May 11, 2011 at 4:43 PM, Yong Zhang <yong.zhang0@...il.com> wrote:
> On Tue, May 10, 2011 at 9:04 PM, Hillf Danton <dhillf@...il.com> wrote:
>> When picking RT task for given CPU,
>> [1] if the cpu is invalid for cpumask test, right result could not be
>
> 'cpu is invalid' means weather we care it or not, it's not real 'invalid'
>
If cpu is not cared, how to determine whether it is allowed for task to run?

>> reached even by further checking nr_cpus_allowed,
>> on the other hand, the input cpu is valid in two cases that
>> pick_next_highest_task_rt() is called, thus the invalid input cpu
>> looks over-concern.
>> [2] if the cpu is valid for cpumask test, further checking
>> nr_cpus_allowed looks overwork, since it is computed based on
>> cpus_allowed,
>
> No, cpumask_test_cpu(cpu, &p->cpus_allowed) doesn't mean
> p->rt.nr_cpus_allowed > 1.
>
If cpu is allowed for task to run, then why more cpus are enforced?

thanks
          Hillf
--
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/