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From: Dipankar Sarma <dipankar@in.ibm.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Sven Dietrich <sdietrich@mvista.com>,
	Daniel Walker <dwalker@mvista.com>, Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, abatyrshin@ru.mvista.com,
	amakarov@ru.mvista.com, emints@ru.mvista.com,
	ext-rt-dev@mvista.com, hzhang@ch.mvista.com, yyang@ch.mvista.com,
	"Witold. Jaworski@Unibw-Muenchen. De" 
	<witold.jaworski@unibw-muenchen.de>,
	arnd.heursch@unibw-muenchen.de
Subject: Re: [ANNOUNCE] Linux 2.6 Real Time Kernel
Date: Thu, 14 Oct 2004 10:39:05 +0530	[thread overview]
Message-ID: <20041014050905.GA6927@in.ibm.com> (raw)
In-Reply-To: <20041012055029.GB1479@elte.hu>

On Tue, Oct 12, 2004 at 07:50:29AM +0200, Ingo Molnar wrote:
> 
> regarding RCU serialization - i think that is the way to go - i dont
> think there is any sensible way to extend RCU to a fully preempted
> model, RCU is all about per-CPU-ness and per-CPU-ness is quite limited 
> in a fully preemptible model.

It seems that way to me too. Long ago I implemented preemptible
RCU, but did not follow it through because I believed it
was not a good idea. The original patch is here :

http://www.uwsg.iu.edu/hypermail/linux/kernel/0205.1/0026.html

This allows read-side critical sections of RCU to be preempted.
It will take a bit of work to re-use it in RCU as of now, but
I don't think it makes sense to do so. My primary concern is
DoS/OOM situation due to preempted tasks holding up RCU.

> 
> could you send those RCU patches (no matter how incomplete/broken)? It's
> the main issue that causes the dcache_lock to be raw still. (and a
> number of dependent locks: fs-writeback.c, inode.c, etc.) We can make
> those RCU changes not impact the normal !PREEMPT_REALTIME locking so it
> might have a chance for upstream merging as well.

I would be interested in this too. 

Thanks
Dipankar

  reply	other threads:[~2004-10-14  5:06 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-10-09  5:59 [ANNOUNCE] Linux 2.6 Real Time Kernel Sven-Thorsten Dietrich
2004-10-09  6:40 ` Lee Revell
2004-10-09  7:33   ` Daniel Walker
2004-10-09  7:42     ` Lee Revell
2004-10-09 23:40       ` Matthias Urlichs
2004-10-09  8:52     ` Lee Revell
2004-10-09 23:20     ` Dave Hansen
2004-10-09 23:24       ` Lee Revell
2004-10-09 10:51 ` Måns Rullgård
2004-10-09 13:15 ` Måns Rullgård
2004-10-09 21:20   ` Lee Revell
2004-10-09 21:35     ` Måns Rullgård
2004-10-09 21:37       ` Lee Revell
2004-10-09 21:45         ` Måns Rullgård
2004-10-09 21:55       ` Lee Revell
2004-10-09 22:21         ` Måns Rullgård
2004-10-09 23:52       ` Lee Revell
2004-10-10  0:05         ` Måns Rullgård
2004-10-10  0:45           ` Lee Revell
2004-10-10  1:05             ` Måns Rullgård
2004-10-10  1:09               ` Lee Revell
2004-10-10  0:43       ` Micha Feigin
2004-10-10  1:08         ` Måns Rullgård
2004-10-09 17:41 ` Karim Yaghmour
2004-10-09 18:30   ` Lee Revell
2004-10-09 21:26     ` stefan.eletzhofer
2004-10-09 19:30       ` Lee Revell
2004-10-09 19:38         ` Måns Rullgård
2004-10-09 21:38         ` stefan.eletzhofer
2004-10-09 19:47           ` Lee Revell
2004-10-09 20:11             ` Karim Yaghmour
2004-10-09 20:14               ` Lee Revell
2004-10-09 20:53                 ` Karim Yaghmour
2004-10-09 20:59                   ` Lee Revell
2004-10-09 20:20             ` Robert Love
2004-10-09 20:25               ` Lee Revell
2004-10-10  1:15 ` Lee Revell
2004-10-10  8:46 ` Ingo Molnar
2004-10-10 19:41   ` Daniel Walker
2004-10-10 19:46     ` Ingo Molnar
2004-10-10 21:20     ` Andrew Morton
2004-10-10 21:59       ` Ingo Molnar
2004-10-11 17:53         ` Daniel Walker
2004-10-11 20:49           ` Ingo Molnar
2004-10-11 21:44             ` Sven Dietrich
2004-10-11 21:54               ` Ingo Molnar
2004-10-11 23:05                 ` Sven Dietrich
2004-10-12  5:50                   ` Ingo Molnar
2004-10-14  5:09                     ` Dipankar Sarma [this message]
2004-10-14  7:18                       ` Ingo Molnar
2004-10-15 14:59                         ` Paul E. McKenney
2004-10-15 15:45                           ` Ingo Molnar
2004-10-15 16:40                             ` Paul E. McKenney
2004-10-15 16:45                               ` Paul E. McKenney
2004-10-17 17:12                       ` Ingo Molnar
2004-10-12 18:50             ` Daniel Walker
2004-10-12 19:46               ` [Ext-rt-dev] " Thomas Gleixner
2004-10-12 20:31                 ` Sven Dietrich
2004-10-12 20:37                   ` Thomas Gleixner
2004-10-13  0:30                   ` George Anzinger
2004-10-12 21:12                 ` Bill Huey
2004-10-12 21:24                   ` Bill Huey
2004-10-12 21:32                     ` Thomas Gleixner
2004-10-12 23:13                       ` Bill Huey
2004-10-12 21:41                   ` Sven Dietrich
2004-10-12 22:57                     ` Bill Huey
2004-10-12 23:17                       ` Adam Heath
2004-10-12 23:36                         ` Lee Revell
2004-10-12 23:25                       ` Thomas Gleixner
2004-10-13  2:02                       ` K.R. Foley
2004-10-13 13:39                       ` Martijn Sipkema
2004-10-13 13:26                         ` La Monte H.P. Yarroll
2004-10-13 15:04                           ` Martijn Sipkema
2004-10-13 14:55                             ` Kurt Wall
2004-10-13 14:52                               ` Christoph Hellwig
2004-10-13 15:56                         ` Lee Revell
2004-10-13 16:13                           ` Robert Love
2004-10-13 17:14                           ` Martijn Sipkema
2004-10-13  3:55                     ` Bill Huey
2004-10-12 22:00                   ` Thomas Gleixner
2004-10-12 22:36                     ` Bill Huey
2004-10-12 23:10                       ` Thomas Gleixner
2004-10-12 23:33                         ` Bill Huey
2004-10-12 23:37                           ` Thomas Gleixner
2004-10-12 23:52                             ` Bill Huey
2004-10-13  0:59                         ` Valdis.Kletnieks
2004-10-10 12:21 ` John Richard Moser
2004-10-10 17:26   ` Lee Revell
2004-10-10 18:45     ` John Richard Moser
2004-10-10 20:20       ` Ingo Molnar
2004-10-10 20:44         ` John Richard Moser
2004-10-10 17:29   ` Daniel Walker
  -- strict thread matches above, loose matches on Subject: below --
2004-10-09 11:38 John Hedditch
2004-10-09 22:54 Sven Dietrich
2004-10-11 15:28 Vadim Lebedev
2004-10-11 15:50 ` Eugeny S. Mints

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