From: Christophe Raffalli <christophe.raffalli@univ-savoie.fr>
To: Xavier Leroy <Xavier.Leroy@inria.fr>
Cc: caml-list <caml-list@inria.fr>
Subject: Re: [Caml-list] Thread and kernel 2.6 pb still there in CVS
Date: Mon, 28 Jun 2004 22:26:20 -0400 [thread overview]
Message-ID: <40E0D34C.2040808@univ-savoie.fr> (raw)
In-Reply-To: <20040628150805.GC7353@yquem.inria.fr>
Xavier Leroy wrote:
>>I tried to submit a change in vouillon's entry in the bug tracking
>>system (classed as not a bug because can not reproduce), but as I am not
>>sure it worked, So I also post this here
>
>
> You should be grateful to Olivier Andrieu, who actually cared to
> submit a bug report along with useful info on 2.6 kernels.
>
Sorry, but I thought continuing an entry in the bug tracking was better
than adding one (but I was unable tu actually make a comment in that
entry !)
> The question I'm currently investigating is whether the call to
> sched_yield() can be omitted, as it's just a scheduling hint. Initial
> experiments suggested that this would hurt fairness (in Caml thread
> scheduling) quite a lot on all platforms other than Linux 2.6.
> More careful experiments that I'm currently conducting suggest that it
> might not be so bad. One can also play games where sched_yield()
> isn't called if there are no other Caml threads waiting for the global
> Caml mutex.
Someone (I do not remember who) suggested a call to select in place of
sched_yield.
My thought about semantics in that
- a system call saying schedule just now or later (like the semantics of
sched_yield in 2.4) only lower the percentage of CPU a thread get,
except if you manage to have your thread "in phase" (I do not know if
this is proper english) with the scheduler.
Then to lower your % of CPU you should use renice (but I do not know if
the semantics of renice is per thread or per processus).
However a system call saying "I do not not need CPU for a while" could
be usefull ... but it should have another name not to break existing
program ... and should have an (optional ?) argument saying how long is
this while.
So I think the 2.6 developper are right, but should have created a new
system call. and let sched yield unchanged.
Any one can feel free to forward my post to a kernel developpers list :-)
> In summary, a solution will eventually be found, but please be
> patient, and submit a bug report next time.
>
> - Xavier Leroy
--
Christophe Raffalli
Université de Savoie
Batiment Le Chablais, bureau 21
73376 Le Bourget-du-Lac Cedex
tél: (33) 4 79 75 81 03
fax: (33) 4 79 75 87 42
mail: Christophe.Raffalli@univ-savoie.fr
www: http://www.lama.univ-savoie.fr/~RAFFALLI
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next prev parent reply other threads:[~2004-06-28 20:26 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-22 22:41 [Caml-list] Why must types be always defined at the top level? Richard Jones
2004-06-22 22:53 ` Markus Mottl
2004-06-22 23:32 ` skaller
2004-06-23 12:01 ` Andreas Rossberg
2004-06-23 14:45 ` skaller
2004-06-23 16:28 ` Andreas Rossberg
2004-06-23 20:21 ` skaller
2004-06-23 20:52 ` skaller
2004-06-24 14:27 ` John Hughes
2004-06-24 16:47 ` Andreas Rossberg
2004-06-24 17:30 ` Markus Mottl
2004-06-24 17:45 ` Xavier Leroy
2004-06-24 19:46 ` John Hughes
2004-06-24 19:56 ` David Brown
2004-06-24 19:57 ` William D. Neumann
2004-06-24 20:13 ` Olivier Andrieu
2004-06-24 23:26 ` Brian Hurt
2004-06-25 10:20 ` skaller
2004-06-25 11:07 ` Basile Starynkevitch [local]
2004-06-25 12:30 ` skaller
2004-06-25 14:38 ` [Caml-list] Thread and kernel 2.6 pb still there in CVS Christophe Raffalli
2004-06-25 16:08 ` [Caml-list] " Marco Maggesi
2004-06-25 16:32 ` Markus Mottl
2004-06-28 15:08 ` [Caml-list] " Xavier Leroy
2004-06-28 18:50 ` Benjamin Geer
2004-06-29 2:26 ` Christophe Raffalli [this message]
[not found] ` <7AFB5F64-C944-11D8-975C-00039310CAE8@inria.fr>
[not found] ` <40E11621.3050709@univ-savoie.fr>
2004-07-05 15:14 ` Christophe Raffalli
2004-07-05 16:34 ` Xavier Leroy
2004-07-06 9:33 ` Alex Baretta
2004-07-08 13:51 ` Christophe Raffalli
2004-07-08 15:03 ` Xavier Leroy
2004-07-09 23:21 ` Donald Wakefield
2004-07-10 10:56 ` Damien Doligez
2004-06-24 23:23 ` [Caml-list] Why must types be always defined at the top level? Brian Hurt
[not found] ` <Pine.LNX.4.44.0406241813370.4202-100000@localhost.localdom ain>
2004-06-26 23:08 ` Dave Berry
2004-06-25 1:59 ` Yaron Minsky
2004-06-24 23:08 ` Brian Hurt
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