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Tue, 17 Sep 2024 10:57:46 GMT Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 65AE058052; Tue, 17 Sep 2024 10:57:46 +0000 (GMT) Received: from smtpav05.dal12v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C5B0C58056; Tue, 17 Sep 2024 10:57:37 +0000 (GMT) Received: from [9.204.206.228] (unknown [9.204.206.228]) by smtpav05.dal12v.mail.ibm.com (Postfix) with ESMTP; Tue, 17 Sep 2024 10:57:37 +0000 (GMT) Message-ID: Date: Tue, 17 Sep 2024 16:27:36 +0530 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/5] perf sched: Introduce stats tool To: Ravi Bangoria Cc: irogers@google.com, namhyung@kernel.org, acme@kernel.org, peterz@infradead.org, swapnil.sapkal@amd.com, yu.c.chen@intel.com, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, rostedt@goodmis.org, vincent.guittot@linaro.org, bristot@redhat.com, adrian.hunter@intel.com, james.clark@arm.com, kan.liang@linux.intel.com, gautham.shenoy@amd.com, kprateek.nayak@amd.com, juri.lelli@redhat.com, yangjihong@bytedance.com, void@manifault.com, tj@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, santosh.shukla@amd.com, ananth.narayan@amd.com, sandipan.das@amd.com, mingo@redhat.com, Madadi Vineeth Reddy References: <20240916164722.1838-1-ravi.bangoria@amd.com> Content-Language: en-US Reply-To: 20240916164722.1838-1-ravi.bangoria@amd.com From: Madadi Vineeth Reddy In-Reply-To: <20240916164722.1838-1-ravi.bangoria@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: W9Xwj_4eqYQ3okMpBkE-XElKP-zJsmJQ X-Proofpoint-GUID: 80uqf8cxpmRt6lT6KPzkgGTyepYm4-gR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-17_02,2024-09-16_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 mlxlogscore=999 priorityscore=1501 phishscore=0 clxscore=1011 malwarescore=0 bulkscore=0 impostorscore=0 spamscore=0 suspectscore=0 mlxscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2409170076 Hi Ravi, On 16/09/24 22:17, Ravi Bangoria wrote: > MOTIVATION > ---------- > > Existing `perf sched` is quite exhaustive and provides lot of insights > into scheduler behavior but it quickly becomes impractical to use for > long running or scheduler intensive workload. For ex, `perf sched record` > has ~7.77% overhead on hackbench (with 25 groups each running 700K loops > on a 2-socket 128 Cores 256 Threads 3rd Generation EPYC Server), and it > generates huge 56G perf.data for which perf takes ~137 mins to prepare > and write it to disk [1]. > > Unlike `perf sched record`, which hooks onto set of scheduler tracepoints > and generates samples on a tracepoint hit, `perf sched stats record` takes > snapshot of the /proc/schedstat file before and after the workload, i.e. > there is almost zero interference on workload run. Also, it takes very > minimal time to parse /proc/schedstat, convert it into perf samples and > save those samples into perf.data file. Result perf.data file is much per.data file is empty after the record. Error: The perf.data data has no samples! Thanks and Regards Madadi Vineeth Reddy > smaller. So, overall `perf sched stats record` is much more light weight > compare to `perf sched record`. > > We, internally at AMD, have been using this (a variant of this, known as > "sched-scoreboard"[2]) and found it to be very useful to analyse impact > of any scheduler code changes[3][4]. > > Please note that, this is not a replacement of perf sched record/report. > The intended users of the new tool are scheduler developers, not regular > users.