From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id B9D4F9000C2 for ; Thu, 7 Jul 2011 14:52:54 -0400 (EDT) Subject: Re: [PATCH] slub: reduce overhead of slub_debug From: Pekka Enberg In-Reply-To: References: <20110626193918.GA3339@joi.lan> Content-Type: text/plain; charset="ISO-8859-1" Date: Thu, 07 Jul 2011 21:52:51 +0300 Message-ID: <1310064771.21902.55.camel@jaguar> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Marcin Slusarz , Matt Mackall , LKML , rientjes@google.com, linux-mm@kvack.org On Thu, 7 Jul 2011, Pekka Enberg wrote: > > Looks good to me. Christoph, David, ? On Thu, 2011-07-07 at 13:17 -0500, Christoph Lameter wrote: > The reason debug code is there is because it is useless overhead typically > not needed. There is no point in optimizing the code that is not run in > production environments unless there are gross performance issues that > make debugging difficult. A performance patch for debugging would have to > cause significant performance improvements. This patch does not do that > nor was there such an issue to be addressed in the first place. Is there something technically wrong with the patch? Quoting the patch email: (Compiling some project with different options) make -j12 make clean slub_debug disabled: 1m 27s 1.2 s slub_debug enabled: 1m 46s 7.6 s slub_debug enabled + this patch: 1m 33s 3.2 s check_bytes still shows up high, but not always at the top. That's significant enough speedup for me! Pekka -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org