linux-kernel - Re: [PATCH v2 1/2] sched/rt: Check to push the task when changing its affinity

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] [day] [month] [year] [list]

Message-ID: <CADcy93ViDQ6594WzPgbo8_T7_=VKBnU=7aSWJhTMM_OcZX=ZZA@mail.gmail.com>
Date:	Sun, 8 Feb 2015 23:19:27 +0800
From:	Xunlei Pang <pang.xunlei@...aro.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Xunlei Pang <xlpang@....com>, lkml <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...il.com>
Subject: Re: [PATCH v2 1/2] sched/rt: Check to push the task when changing its affinity

On 8 February 2015 at 22:55, Xunlei Pang <pang.xunlei@...aro.org> wrote:
> Hi Steve,
>
> On 7 February 2015 at 05:09, Steven Rostedt <rostedt@...dmis.org> wrote:
>> On Thu,  5 Feb 2015 23:59:33 +0800
>>
>>         if (task_running(rq, p)) {
>>                 if (cpumask_test_cpu() && cpupri_find()) {
>>                 }
>>         } else {
>>                 direct push = 1
>>
>> Also, is the copy of cpus_allowed only done so that cpupri_find is
>> called? If so maybe move it in there too:
>>
>>         if (task_running(rq, p)) {
>>                 if (!cpumask_test_cpu())
>>                         goto update;
>>
>>                 cpumask_copy(&p->cpus_allowed, new_mask);
>>                 p->nr_cpus_allowed = new_weight;
>>
>>                 if (!cpupri_find())
>>                         goto update;
>>
>>                 [...]
>>
>> This way we avoid the double copy of cpumask unless we truly need to do
>> it.
>
> The new_mask can also be used by direct_push case, so I think it's ok.

I guess you mean to avoid the copy if cpumask_test_cpu() is false.
I think this function is not the hot path, making this will make the code
indents too many times or not so good to look, a little awful.

Thanks,
Xunlei
--
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/