From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751349AbeECIcV (ORCPT ); Thu, 3 May 2018 04:32:21 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:47206 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751127AbeECIcQ (ORCPT ); Thu, 3 May 2018 04:32:16 -0400 Subject: Re: [PATCH v3 0/9] trace_uprobe: Support SDT markers having reference count (semaphore) To: mhiramat@kernel.org, oleg@redhat.com Cc: Ravi Bangoria , peterz@infradead.org, srikar@linux.vnet.ibm.com, rostedt@goodmis.org, acme@kernel.org, ananth@linux.vnet.ibm.com, akpm@linux-foundation.org, alexander.shishkin@linux.intel.com, alexis.berlemont@gmail.com, corbet@lwn.net, dan.j.williams@intel.com, jolsa@redhat.com, kan.liang@intel.com, kjlx@templeofstupid.com, kstewart@linuxfoundation.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, milian.wolff@kdab.com, mingo@redhat.com, namhyung@kernel.org, naveen.n.rao@linux.vnet.ibm.com, pc@us.ibm.com, tglx@linutronix.de, yao.jin@linux.intel.com, fengguang.wu@intel.com, jglisse@redhat.com References: <20180417043244.7501-1-ravi.bangoria@linux.vnet.ibm.com> From: Ravi Bangoria Date: Thu, 3 May 2018 14:02:00 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180417043244.7501-1-ravi.bangoria@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18050308-0020-0000-0000-0000041872DA X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050308-0021-0000-0000-000042AD934F Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-03_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805030081 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/17/2018 10:02 AM, Ravi Bangoria wrote: > Userspace Statically Defined Tracepoints[1] are dtrace style markers > inside userspace applications. Applications like PostgreSQL, MySQL, > Pthread, Perl, Python, Java, Ruby, Node.js, libvirt, QEMU, glib etc > have these markers embedded in them. These markers are added by developer > at important places in the code. Each marker source expands to a single > nop instruction in the compiled code but there may be additional > overhead for computing the marker arguments which expands to couple of > instructions. In case the overhead is more, execution of it can be > omitted by runtime if() condition when no one is tracing on the marker: > > if (reference_counter > 0) { > Execute marker instructions; > } > > Default value of reference counter is 0. Tracer has to increment the > reference counter before tracing on a marker and decrement it when > done with the tracing. Hi Oleg, Masami, Can you please review this :) ? Thanks.