From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27587 invoked by alias); 5 Apr 2006 12:03:29 -0000 Received: (qmail 27579 invoked by uid 22791); 5 Apr 2006 12:03:29 -0000 X-Spam-Status: No, hits=-2.6 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Wed, 05 Apr 2006 12:03:27 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id k35C3PHc017774; Wed, 5 Apr 2006 08:03:25 -0400 Received: from pobox.toronto.redhat.com (pobox.toronto.redhat.com [172.16.14.4]) by int-mx1.corp.redhat.com (8.12.11.20060308/8.11.6) with ESMTP id k35C3P3h002203; Wed, 5 Apr 2006 08:03:25 -0400 Received: from touchme.toronto.redhat.com (IDENT:postfix@touchme.toronto.redhat.com [172.16.14.9]) by pobox.toronto.redhat.com (8.12.8/8.12.8) with ESMTP id k35C3PlO032461; Wed, 5 Apr 2006 08:03:25 -0400 Received: from ton.toronto.redhat.com (ton.toronto.redhat.com [172.16.14.15]) by touchme.toronto.redhat.com (Postfix) with ESMTP id 1570A8002B7; Wed, 5 Apr 2006 08:03:25 -0400 (EDT) Received: from ton.toronto.redhat.com (localhost.localdomain [127.0.0.1]) by ton.toronto.redhat.com (8.13.1/8.13.1) with ESMTP id k35C3Ok6027848; Wed, 5 Apr 2006 08:03:24 -0400 Received: (from fche@localhost) by ton.toronto.redhat.com (8.13.1/8.13.1/Submit) id k35C3N1a027840; Wed, 5 Apr 2006 08:03:23 -0400 X-Authentication-Warning: ton.toronto.redhat.com: fche set sender to fche@redhat.com using -f To: Guang Lei Li Cc: systemtap@sources.redhat.com Subject: Re: adding statements in alias definition as epilogue References: <20060405012447.GC16498@redhat.com> From: fche@redhat.com (Frank Ch. Eigler) Date: Wed, 05 Apr 2006 12:03:00 -0000 In-Reply-To: Message-ID: User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2006-q2/txt/msg00039.txt.bz2 Guang Lei Li writes: > [...] > probe addevent.tskdispatching.* {} > > will cause both addevent.tskdispatch.cpuidle.backtrace & > addevent.tskdispatch.cpuidle to be triggered. Actually, it doesn't: the wildcard only consumes one component of the probe point name. > > This assumes that per-probe backtrace configuration makes more sense > > than, say, a single global variable. > > 'backtrace' used inside the probe definitions is a local variable, which > is cheaper than using a global variable. Only slightly (one extra shared lock). > And it also enables to turn on/off backtrace for each event > separately instead of turn on/off all backtraces as a whole. I see that, but is this capability important & useful? Plus, apropos an earlier message, how does the concept of high-performance binary tracing mesh at all with slow and bulky backtrace generation? > [...] Besides my specific need of alias definition as epilogue, I > think it is also useful if you want a filter: [...] > > probe derived_probe := alias_with_filter_codes { > filter_on = 1 > scsi_lun = 2 > scsi_dev_major = 3 > } This style of usage could be accommodated with explicit code (analogous to "if (target() != pid()) next") instead of alias epilogues. - FChE