linux-kernel - Re: [PATCH v4] sched: fix init 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: <CAKfTPtAq4GWoc8oOaUt17ZePfa4PMq7NvPEZYrqo2cvDpGwsWQ@mail.gmail.com>
Date:	Tue, 26 Feb 2013 17:41:08 +0100
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org,
	peterz@...radead.org, mingo@...nel.org, rostedt@...dmis.org,
	efault@....de
Subject: Re: [PATCH v4] sched: fix init NOHZ_IDLE flag

On 26 February 2013 14:16, Frederic Weisbecker <fweisbec@...il.com> wrote:
> 2013/2/22 Vincent Guittot <vincent.guittot@...aro.org>:
>> I wanted to avoid having to use the sd pointer for testing NOHZ_IDLE
>> flag because it occurs each time we go into idle but it seems to be
>> not easily feasible.
>> Another solution could be to add a synchronization step between
>> rcu_assign_pointer(dom 1, NULL) and create new domain to ensure that
>> all pending access to old sd values, has finished but this will imply
>> a potential delay in the rebuild  of sched_domain and i'm not sure
>> that it's acceptable
>
> The other issue is that we'll need to abuse the fact that struct
> sched_domain is per cpu in order to store a per cpu state there.
> That's a bit ugly but at least safer.
>
> Also, are struct sched_group and struct sched_group_power shared among
> several CPUs or are they per CPUs allocated as well? I guess they
> aren't otherwise nr_cpus_busy would be pointless.

Yes they are shared between CPUs, per cpu sched_domain points to same
sched_group and sched_group_power.
--
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/