From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [patch 4/4] KVM-trace port to tracepoints Date: Wed, 23 Jul 2008 11:08:29 +0300 Message-ID: <4886E6FD.4090200@qumranet.com> References: <20080717155724.897537670@polymtl.ca> <20080717160003.359557938@polymtl.ca> <487F7800.4010502@siemens.com> <20080717172853.GB29855@Krystal> <488604F8.1040008@siemens.com> <48862B01.7070907@qumranet.com> <1216799346.7257.125.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jan Kiszka , Mathieu Desnoyers , akpm@linux-foundation.org, Ingo Molnar , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, "Feng(Eric) Liu" To: Peter Zijlstra Return-path: Received: from il.qumranet.com ([212.179.150.194]:48721 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750721AbYGWIIb (ORCPT ); Wed, 23 Jul 2008 04:08:31 -0400 In-Reply-To: <1216799346.7257.125.camel@twins> Sender: kvm-owner@vger.kernel.org List-ID: Peter Zijlstra wrote: > On Tue, 2008-07-22 at 21:46 +0300, Avi Kivity wrote: > >> Jan Kiszka wrote: >> >>> That's true - as long as you don't have to add/remove/modify >>> tracepoints. I had to do this job in the past (not for KVM). Having 1 >>> spot in 1 file (based on generic probes) would be handier in that case >>> than 5 spots in 3 files. But if the KVM tracepoints are considered >>> stable in their number and structure, that shouldn't be an issue here. >>> >>> >>> >> Tracepoints aren't stable; they are artefacts of the implementation. >> > > Which IMHO makes it unsuitable for trace_mark() as that will be exported > to user-space, and every time you change your tracepoints you'll change > user visible things - not nice. > They are used for debugging (mostly performance related), so changes are expected. What uses of trace_mark() depend on a stable interface? blktrace? -- error compiling committee.c: too many arguments to function