From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751962AbXCOU2j (ORCPT ); Thu, 15 Mar 2007 16:28:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751963AbXCOU2i (ORCPT ); Thu, 15 Mar 2007 16:28:38 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:49851 "EHLO netops-testserver-3.corp.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751962AbXCOU2h (ORCPT ); Thu, 15 Mar 2007 16:28:37 -0400 Date: Thu, 15 Mar 2007 13:28:36 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Andrew Morton cc: linux-mm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [QUICKLIST 0/4] Arch independent quicklists V2 In-Reply-To: <20070313042742.e35b7511.akpm@linux-foundation.org> Message-ID: References: <20070313071325.4920.82870.sendpatchset@schroedinger.engr.sgi.com> <20070313005334.853559ca.akpm@linux-foundation.org> <20070313042742.e35b7511.akpm@linux-foundation.org> 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 Tue, 13 Mar 2007, Andrew Morton wrote: > > 1. We need to support other states of pages other than zeroed. > > What does this mean? pgd are not completely zeroed. They contain mappings that are always present. Thus the state is not a zeroed state. > > 2. Prezeroing does not make much sense if a large portion of the > > page is being used. Performance is better if the whole page > > is zeroed directly before use.Prezeroing only makes sense for sparse > > allocations like the page table pages. > > This is not related to the above discussion. Really? I definitely see the word prezeroing in the discussion. > > I already tried that 3 years ago and there was *no* benefit for usual > > users of the a page allocator. The advantage exists only if a small > > portion of the page is used. F.e. For one cacheline there was a 4x > > improvement. See lkml archives for prezeroing. > > Unsurprised. Were non-temporal stores tried? Yes with no material change. The work lead to making ia64 use non temporal stores for spin unlock but it was not useful for prezeroing.