Re: -mmX 4G patches feedback

From: Andrea Arcangeli <andrea@suse.de>
To: Eric Whiting <ewhiting@amis.com>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: -mmX 4G patches feedback
Date: Tue, 6 Apr 2004 00:16:41 +0200	[thread overview]
Message-ID: <20040405221641.GN2234@dualathlon.random> (raw)
In-Reply-To: <4071D11B.1FEFD20A@amis.com>

On Mon, Apr 05, 2004 at 03:35:23PM -0600, Eric Whiting wrote:
> 4G of virtual address is what we need. Virtual address space is why the -mmX
> 4G/4G patches are useful. In this application it is single processes (usually

Indeed.

> 3.5:1.5 appears to be a 2.4.x kernel patch only right?

Martin has a port for 2.6 in the -mjb patchset (though it only works
with PAE disabled but there are patches floating around to make it work
at not noticeable cost with PAE enabled too).

Note if you never run sysscalls you're probably fine with 4:4, I'd
recommend to lower the timer irq back to 100 HZ though (2000 mm switch
per second is way too much for number crunching with 4:4, it's way too much
even with 3:1, with 3:1 is something like 1% slowdown just due the more
frequent irqs [on a mean 1-2Ghz box], with 4:4 should be a lot lot worse
than that).