From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265022AbUHMMSF (ORCPT ); Fri, 13 Aug 2004 08:18:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265027AbUHMMSF (ORCPT ); Fri, 13 Aug 2004 08:18:05 -0400 Received: from colin2.muc.de ([193.149.48.15]:16134 "HELO colin2.muc.de") by vger.kernel.org with SMTP id S265022AbUHMMSB (ORCPT ); Fri, 13 Aug 2004 08:18:01 -0400 Date: 13 Aug 2004 14:18:00 +0200 Date: Fri, 13 Aug 2004 14:18:00 +0200 From: Andi Kleen To: Ingo Molnar Cc: linux-kernel@vger.kernel.org Subject: Re: [patch] Latency Tracer, voluntary-preempt-2.6.8-rc4-O6 Message-ID: <20040813121800.GA68967@muc.de> References: <2mkTt-BZ-11@gated-at.bofh.it> <2nrJd-7Dx-19@gated-at.bofh.it> <2ouFe-2vz-63@gated-at.bofh.it> <2rfT9-5wi-17@gated-at.bofh.it> <2rF1c-6Iy-7@gated-at.bofh.it> <2sxEs-46P-1@gated-at.bofh.it> <2sCkH-7i5-15@gated-at.bofh.it> <2sHu9-2EW-31@gated-at.bofh.it> <20040813121502.GA18860@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040813121502.GA18860@elte.hu> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 13, 2004 at 02:15:02PM +0200, Ingo Molnar wrote: > > * Andi Kleen wrote: > > > >> Interesting results. One of the problems is kallsyms_lookup, > > >> triggered by the printks: > > > > > > yeah - kallsyms_lookup does a linear search over thousands of symbols. > > > Especially since /proc/latency_trace uses it too it would be worthwile > > > to implement some sort of binary searching. > > > > Or just stick some cond_sched()s in there. It was designed to be slow, > > but there are no locking issues. > > the speedup would be important: even on a 2GHz box reading 10,000 trace > entries takes a couple of seconds. That's because you're abusing it - it was never designed to process that much data. With binary search you would need to backward search to find the stem for the stem compression. It's probably doable, but would be a bit ugly I guess. -Andi