From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754804Ab0IURgH (ORCPT ); Tue, 21 Sep 2010 13:36:07 -0400 Received: from one.firstfloor.org ([213.235.205.2]:44686 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752475Ab0IURgF (ORCPT ); Tue, 21 Sep 2010 13:36:05 -0400 Message-ID: <140ee1c060f22286fe2f4d81170f76be.squirrel@www.firstfloor.org> In-Reply-To: <1285082049.23122.1930.camel@gandalf.stny.rr.com> References: <20100921131232.GA3024@one.firstfloor.org> <20100921143555.GA2873@redhat.com> <0e1f6b339e72a449fed0df7b801da607.squirrel@www.firstfloor.org> <1285082049.23122.1930.camel@gandalf.stny.rr.com> Date: Tue, 21 Sep 2010 19:36:00 +0200 Subject: Re: [PATCH 03/10] jump label v11: base patch From: "Andi Kleen" To: "Steven Rostedt" Cc: "Andi Kleen" , "Jason Baron" , linux-kernel@vger.kernel.org, mingo@elte.hu, mathieu.desnoyers@polymtl.ca, hpa@zytor.com, tglx@linutronix.de, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com, fweisbec@gmail.com, avi@redhat.com, davem@davemloft.net, vgoyal@redhat.com, sam@ravnborg.org, tony@bakeyournoodle.com User-Agent: SquirrelMail/1.4.21 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Priority: 3 (Normal) Importance: Normal Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Tue, 2010-09-21 at 16:41 +0200, Andi Kleen wrote: >> > >> > So there are ~150 tracepoints, but this code is also being proposed >> for >> > use with 'dynamic debug' of which there are > 1000, and I'm hoping for >> > more users moving forward. >> >> Even 1000 is fine to walk, but if it was sorted a binary search >> would be much faster anyways. That is then you would still >> need to search for each module, but that is a relatively small >> number (< 100) > > xfs has > 100 tracepoints Doesn > >> >> > Also, I think the hash table deals nicely with modules. >> >> Maybe but it's also a lot of code. And it seems to me >> that it is optimizing the wrong thing. Simpler is nicer. > > I guess simplicity is in the eye of the beholder. I find hashes easier > to deal with than binary searching sorted lists. Every time you add a > tracepoint, you need to resort the list. The only time you add one is when you load a module, right? When you do that you only sort the section of the new module. > Hashes are much easier to deal with and scale nicely. I don't think > there's enough rational to switch this to a binary list. Well problem is that the code is very complicated today. I suspect this could be done much simpler if it wasn't so overengin -Andi