From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754066AbZEKH2U (ORCPT ); Mon, 11 May 2009 03:28:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752327AbZEKH2G (ORCPT ); Mon, 11 May 2009 03:28:06 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:61167 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751600AbZEKH2F (ORCPT ); Mon, 11 May 2009 03:28:05 -0400 Message-ID: <4A07D3B3.10605@cn.fujitsu.com> Date: Mon, 11 May 2009 15:28:51 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Mathieu Desnoyers CC: linux-kernel@vger.kernel.org, mingo@elte.hu, fweisbec@gmail.com, rostedt@goodmis.org, zhaolei@cn.fujitsu.com, laijs@cn.fujitsu.com, Li Zefan Subject: Re: [PATCH v3] ftrace: add a tracepoint for __raise_softirq_irqoff() References: <49FFDF9C.7040505@cn.fujitsu.com> <20090505161604.GA15524@Krystal> In-Reply-To: <20090505161604.GA15524@Krystal> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mathieu Desnoyers wrote: > * Xiao Guangrong (xiaoguangrong@cn.fujitsu.com) wrote: >> From: Mathieu Desnoyers >> >> +#ifdef CONFIG_TRACEPOINTS >> +extern void __raise_softirq_irqoff(unsigned int nr); >> +#else >> #define __raise_softirq_irqoff(nr) do { or_softirq_pending(1UL << (nr)); } while (0) > > Can you put the > trace_irq_softirq_raise(nr); > > directly in the define rather than adding this weird CONFIG_TRACEPOINTS? > (and change the define for a static inline), something like : > > static inline void __raise_softirq_irqoff(unsigned int nr) > { > trace_irq_softirq_raise(nr); > or_softirq_pending(1UL << (nr); > } > > This would ensure we don't add a function call on the > __raise_softirq_irqoff() fast-path. > We did this in v2, and we think it is better for same reason. But ... > Beware of circular include dependencies though. The tracepoints are > meant not to have this kind of problems (I try to keep the dependencies > very minimalistic), but I wonder if Steven's TRACE_EVENT is now ok on > this aspect. > We encount this type of problem in v2. So we move to this version(v3). > If TRACE_EVENT happens to pose problems with circular header > dependencies, then try moving to the DECLARE_TRACE/DEFINE_TRACE scheme > which has been more thoroughly tested as a first step. > IMHO, TRACE_EVENT framework is better for its more generic as ingo said, and it also provide ftrace support which means user can view tracepoint information from /debug/tracing/events. Although this TRACE_EVENT happens to expose problems with circular header dependencies, we should not refuse using TRACE_EVENT, instead we should try to fix it for the whole TRACE_EVENT facility later. Thanks > Mathieu >