From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265305AbTL0ECG (ORCPT ); Fri, 26 Dec 2003 23:02:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265307AbTL0ECG (ORCPT ); Fri, 26 Dec 2003 23:02:06 -0500 Received: from fw.osdl.org ([65.172.181.6]:39075 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S265305AbTL0ECD (ORCPT ); Fri, 26 Dec 2003 23:02:03 -0500 Date: Fri, 26 Dec 2003 20:01:57 -0800 (PST) From: Linus Torvalds To: Andrea Arcangeli cc: Nick Craig-Wood , William Lee Irwin III , linux-kernel@vger.kernel.org, Rohit Seth Subject: Re: 2.6.0 Huge pages not working as expected In-Reply-To: <20031227033620.GG1676@dualathlon.random> Message-ID: References: <20031226105433.GA25970@axis.demon.co.uk> <20031226115647.GH27687@holomorphy.com> <20031226201011.GA32316@axis.demon.co.uk> <20031227033620.GG1676@dualathlon.random> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 27 Dec 2003, Andrea Arcangeli wrote: > > well, at least on the alpha the above mode = 1 is reproducibly a lot > better (we're talking about a wall time 2/3 times shorter IIRC) than > random placement. The l2 is huge and one way cache associative, What kind of strange and misguided hw engineer did that? I can understand a one-way L1, simply to keep the cycle time low, but what's the point of a one-way L2? Braindead external cache controller? > The current patch is for 2.2 with an horrible API (it uses a kernel > module to set those params instead of a sysctl, despite all the real > code is linked into the kernel), while developing it I only focused on > the algorithms and the final behaviour in production. the engine to ask > the allocator a page of the right color works O(1) with the number of > free pages and it's from Jason. Does it keep fragmentation down? That's the problem that Davem had in one of his cache-coloring patches: it worked well enough if you had lots of memory, but it _totally_ broke down when memory was low. You couldn't allocate higher-order pages at all after a while because of the fragmented memory. Linus