linux-kernel - Re: atomic RAM ?

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Message-ID: <20100412125402.GA22773@ucw.cz>
Date:	Mon, 12 Apr 2010 14:54:03 +0200
From:	Pavel Machek <pavel@....cz>
To:	Michael Schnell <mschnell@...ino.de>
Cc:	David Newall <davidn@...idnewall.com>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: atomic RAM ?

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

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