From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756016AbdESJJR (ORCPT ); Fri, 19 May 2017 05:09:17 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:49128 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755400AbdESJJO (ORCPT ); Fri, 19 May 2017 05:09:14 -0400 Date: Fri, 19 May 2017 11:09:10 +0200 From: Peter Zijlstra To: Konstantin Khlebnikov Cc: linux-kernel@vger.kernel.org, Ingo Molnar Subject: Re: [PATCH] lockdep: do not count lock class operations without CONFIG_DEBUG_LOCKDEP Message-ID: <20170519090910.fubv3c3ozfckavi3@hirez.programming.kicks-ass.net> References: <149517756125.33116.15222517572640587072.stgit@buzz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <149517756125.33116.15222517572640587072.stgit@buzz> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 19, 2017 at 10:06:01AM +0300, Konstantin Khlebnikov wrote: > Currently this counter shown in /proc/lockdep if CONFIG_DEBUG_LOCKDEP=y > This patch disables it completely if this option is disabled. > > This counter might be useful for debugging lockdep itself, but for normal > debugging it seems useless. Lockstat provides more detailed statistics. > > This atomic_inc is a hot spot inside __lock_acquire() for debug kernel. > > With patch "netperf -H localhost" shows some boost: 2500 -> 2600 Nothing against these patches, but I do wonder why you're performance optimizing debug kernels ;-)