linux-kernel - Re: [patch] CFS scheduler, -v15

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:	Wed, 6 Jun 2007 13:19:01 +0200
From:	"Dmitry Adamushko" <dmitry.adamushko@...il.com>
To:	vatsa@...ibm.com
Cc:	"Balbir Singh" <balbir@...ux.vnet.ibm.com>,
	"Ingo Molnar" <mingo@...e.hu>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [patch] CFS scheduler, -v15

On 06/06/07, Srivatsa Vaddagiri <vatsa@...ibm.com> wrote:
> [ ... ]
> > > This way, on RT -> NORMAL transition.. some 'delta_exec' ( between
> > > deactivate_task() ---> activate_task() ) will be accounted later as if
> > > the task was 'sched_fair_class' during this time.. which I think makes
> > > some sense. What do you think?
> > >
> >
> > Why not do it explicitly in __setscheduler() if the new policy is SCHED_NORMAL
> > or SCHED_BATCH.
>
> Yes this is the approach I prefer, because we burden the fast/normal
> path less that way (RT->NORMAL transition is not common).

I don't think that rt_sched_class :: dequeue_task_rt() is in any of
such "fast pathes" that we should really care about an additional
math. operation.

If this approach is ok, logically-wise (no side effects from a short
'delta_exec', esp. on RT -> NORMAL).. I think it's better as it keeps
the 'sched_class' interface simpler.

> That's why I
> was considering a set_curr_task() method in fair_sched_class which will
> be invoked in __setscheduler() if the new policy of currently running
> task happens to be SCHED_NORMAL/BATCH. Alternately if the new policy of
> currently running task happens to be SCHED_FIFO (and its old policy was
> SCHED_NORMAL) we need to invoke put_prev_task() method (so that
> fair_clock etc is updated based on outgoing task's execution time in
> SCHED_NORMAL class).

rt_sched_class :: put_prev_task() from __setscheduler() ? But it's not
supposed to be called from here, logically-wise. You just rely on its
current behavior (which is only about updating 'exec_start' and
'exec_sum') -- that's just bad. Maybe I misunderatood your intention
though..


> --
> Regards,
> vatsa
>

-- 
Best regards,
Dmitry Adamushko
-
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/