From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9327 invoked by alias); 9 Aug 2016 15:28:01 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 9309 invoked by uid 89); 9 Aug 2016 15:28:00 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=H*MI:sk:b95a09f, H*i:sk:b95a09f, H*f:sk:b95a09f, quality X-HELO: mail-wm0-f53.google.com Received: from mail-wm0-f53.google.com (HELO mail-wm0-f53.google.com) (74.125.82.53) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Tue, 09 Aug 2016 15:27:50 +0000 Received: by mail-wm0-f53.google.com with SMTP id f65so38916295wmi.0 for ; Tue, 09 Aug 2016 08:27:50 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:from:organization :message-id:date:user-agent:mime-version:in-reply-to :content-transfer-encoding; bh=U7iC5Fu2Cd6BYVZiFbl8dl67VNcNEPenJWk+3mHEfvY=; b=hCcH1F0mPmvvb+YImBD3Qc1vAE7WmbL1045ZE8VuqfnOUzGCK9J0QSYy5hp2EyAwSy GUCfgHTQsM0OrCQWgNEmD2tETi7bA9+RnqrEULb16MRKm/pW+ikGmd9LJm1wHf87jATb wuIKIZVTNoASuxzA4AH+MMbbL5CAlDyRd3zfzBQOYekSbxqWvA5OKQ0Kh5S3BKZFbpVf UiQpFfEsVh76thZwp/WI0zE8X5kfxx0B6udj2Q6mazEyr3eBMpGIBt4Neri9XH82DQWm EyQViKQ6VblaJ+co0PAC2cMeBhEuNVRL++yS3nEbH9tPsvt/qdhJUZHtiBGYYONLYL5L i9ww== X-Gm-Message-State: AEkoouspt8msKLHx/0geoPbu4wgrD+WKUGuX3BJu0egzhbLmlRLEUvF0FrSOUjFCdcwk1A== X-Received: by 10.194.222.168 with SMTP id qn8mr22142293wjc.172.1470756467424; Tue, 09 Aug 2016 08:27:47 -0700 (PDT) Received: from avi.cloudius-systems.com ([37.142.229.250]) by smtp.gmail.com with ESMTPSA id ya1sm28174787wjb.23.2016.08.09.08.27.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Aug 2016 08:27:45 -0700 (PDT) Subject: Re: Some newbie questions To: David Smith , systemtap@sourceware.org References: From: Avi Kivity Message-ID: Date: Tue, 09 Aug 2016 15:28:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-q3/txt/msg00147.txt.bz2 On 08/09/2016 06:17 PM, David Smith wrote: > On 08/09/2016 01:51 AM, Avi Kivity wrote: >> >> On 08/08/2016 05:58 PM, David Smith wrote: >>>> 2. Inlined functions >>>> >>>> From the manual pages, it seems that inlined functions can be probed >>>> (minus the .return probe), but I just get an error: >>>> >>>> semantic error: while resolving probe point: identifier 'process' at >>>> script/home/avi/seastar/debug/task-latency.stap:3:7 >>>> source: probe >>>> process("scylla").function("reactor::run_tasks()") { >>>> ^ >>>> >>>> semantic error: no match (similar functions: >>>> _ZN7reactor14run_exit_tasksEv, statfs, dup, mkdir, ntohs) >>> We're at the mercy of the compiler and the quality of the debuginfo it >>> produces here when looking for inlined functions. >>> >>> If you want to investigate further here, you'll need to do the following: >>> >>> # eu-readelf -N --debug-dump=info scylla > scylla.log >>> >>> In scylla.log, look and see if you can find a subprogram with the name >>> of the function you are interested in. >> [1417f4] subprogram >> external (flag_present) Yes >> name (strp) "run_tasks" >> decl_file (data1) 5 >> decl_line (data2) 812 >> linkage_name (strp) >> "_ZN7reactor9run_tasksER15circular_bufferISt10unique_ptrI4taskSt14default_deleteIS2_EESaIS5_EE" >> >> declaration (flag_present) Yes >> object_pointer (ref4) [141808] >> sibling (ref4) [141813] >> [141808] formal_parameter >> type (ref4) [1423bd] >> artificial (flag_present) Yes >> [14180d] formal_parameter >> type (ref4) [14a8a8] > According to the above, that function isn't inlined. You might just try > the following to see what functions stap can see: > > # stap -l 'process("scylla").function("*")' | grep run_tasks process("/usr/bin/scylla").function("run_tasks@core/reactor.cc:1362") Strangely not qualified by "reactor::". >> I also switched to timer.profile. What's its resolution on normal >> machines? > timer.profile probe resolution is CONFIG_HZ. Check your kernel config > and see "man stapprobes" for more details. > Thanks.