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From: Pavel Machek <pavel@ucw.cz>
To: Michael Schnell <mschnell@lumino.de>
Cc: David Newall <davidn@davidnewall.com>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: atomic RAM ?
Date: Mon, 12 Apr 2010 14:54:03 +0200	[thread overview]
Message-ID: <20100412125402.GA22773@ucw.cz> (raw)
In-Reply-To: <4BBDA742.9010507@lumino.de>

Hi!

> OTOH, to do FUTEX in full (MMU) - Linux, atomic operations are
> definitively necessary, as in Userland you can't disable the interrupt
> without a Kernel call (which to avoid FUTEX is all about.) Currently the

You could create unpriviledged 'disable interrupts for 10
instructions' and 'test if interrupts are still disabled'
instructions, and base your mutex implementation on that.

But you'll have to stop calling it futex at that point...

Or you could just optimize syscalls to be really fast...
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  reply	other threads:[~2010-04-12 12:54 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-08  7:32 atomic RAM ? Michael Schnell
     [not found] ` <4BBDA1CB.3070204@davidnewall.com>
2010-04-08  9:52   ` Michael Schnell
2010-04-12 12:54     ` Pavel Machek [this message]
2010-04-14  8:42       ` Michael Schnell
     [not found] ` <k2gbca41b4c1004080243nc45a10aereaae18557808c943@mail.gmail.com>
2010-04-08 10:12   ` Michael Schnell
2010-04-08 10:45 ` Alan Cox
2010-04-08 12:11   ` Michael Schnell
2010-04-08 12:14     ` David Miller
2010-04-08 12:30       ` Michael Schnell
2010-04-08 14:15         ` Arnd Bergmann
2010-04-09 10:54           ` Michael Schnell
     [not found]           ` <4BBEECC8.10005@lumino.de>
     [not found]             ` <201004091714.04990.arnd@arndb.de>
2010-04-12  9:58               ` Michael Schnell
2010-04-12 15:02                 ` Arnd Bergmann
2010-04-13 10:11                   ` Michael Schnell
     [not found]                 ` <u2j42b5547a1004120845x87d7f2f7wd4acea1144153dd6@mail.gmail.com>
2010-04-13  8:39                   ` [Nios2-dev] " Michael Schnell
2010-04-08 13:37     ` Alan Cox
2010-04-09 10:55       ` Michael Schnell
2010-04-09 11:54         ` Alan Cox
2010-04-09 12:53           ` Michael Schnell
2010-04-09 13:15             ` Alan Cox
2010-04-09 13:14               ` Michael Schnell
2010-04-09 13:32               ` Michael Schnell
2010-04-14 12:46       ` Michael Schnell
2010-04-14 12:57         ` Alan Cox
2010-04-14 14:38           ` Michael Schnell
2010-04-09  1:36 ` Mike Frysinger
2010-04-09  9:23   ` Michael Schnell

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