Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753351Ab0HBMYU (ORCPT ); Mon, 2 Aug 2010 08:24:20 -0400 Received: from casper.infradead.org ([85.118.1.10]:44072 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751827Ab0HBMYT convert rfc822-to-8bit (ORCPT ); Mon, 2 Aug 2010 08:24:19 -0400 Subject: Re: [PATCH RFC] perf lock: Add new event "lock_acquired_waittime" for contention analysis From: Peter Zijlstra To: Hitoshi Mitake Cc: Frederic Weisbecker , Steven Rostedt , linux-kernel@vger.kernel.org, h.mitake@gmail.com, Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo , Jason Baron , Xiao Guangrong , Jens Axboe In-Reply-To: <4C5507F2.7090503@dcl.info.waseda.ac.jp> References: <1279990529-8798-1-git-send-email-mitake@dcl.info.waseda.ac.jp> <20100728163946.GB5394@nowhere> <4C5507F2.7090503@dcl.info.waseda.ac.jp> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 02 Aug 2010 14:23:04 +0200 Message-ID: <1280751784.1923.146.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 800 Lines: 20 On Sun, 2010-08-01 at 14:36 +0900, Hitoshi Mitake wrote: > I want to make lockdep production kernel feature with dynamic > patching. Not really feasible. Note that enabling lockdep grows the size of spinlock_t (and others) quite significantly. Then there is the problem that you need to pass all tasks through some quiesent state in order to enable lockdep (there must be a guarantee of no locks held). Now, we could possibly make it all work, but I'm not at all convinced we want to pay the price, which is a much _much_ more complex infrastructure. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/