From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 9 Apr 2007 09:40:29 -0700 From: William Lee Irwin III Subject: Re: [PATCH 1/4] x86_64: (SPARSE_VIRTUAL doubles sparsemem speed) Message-ID: <20070409164029.GT2986@holomorphy.com> References: <20070401071029.23757.78021.sendpatchset@schroedinger.engr.sgi.com> <200704011246.52238.ak@suse.de> <1175544797.22373.62.camel@localhost.localdomain> <461169CF.6060806@google.com> <4614E293.3010908@shadowen.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Andy Whitcroft , Martin Bligh , Dave Hansen , Andi Kleen , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, KAMEZAWA Hiroyuki List-ID: On Sat, Apr 07, 2007 at 03:06:13PM -0700, Christoph Lameter wrote: > +/* > + * Performance Counters and Measurement macros > + * (C) 2005 Silicon Graphics Incorporated > + * by Christoph Lameter , April 2005 > + * > + * Counters are calculated using the cycle counter. If a process > + * is migrated to another cpu during the measurement then the measurement > + * is invalid. > + * > + * We cannot disable preemption during measurement since that may interfere > + * with other things in the kernel and limit the usefulness of the counters. > + */ Whatever's going on with the rest of this, I really like this instrumentation patch. It may be worthwhile to allow pc_start() to be overridden so things like performance counter MSR's are usable, but the framework looks very useful. -- wli -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org