From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E1D011E7660 for ; Fri, 15 Aug 2025 08:34:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755246900; cv=none; b=dwSf2SQ68dI+5i7vLYURirTElJ8T46iIPpvwRVIjx5bP5EBN4YTAQr+KZfOVCzwWK9xf/FkEdBRJUCaDSOQ0e4/TCaxRRcws2+RW4rdXr96AXUljRn0j8yLiIBlmpBQudoCOJyh3xbmVL1rnWvrCT90A+4jlrkawfswSGTnwnDs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755246900; c=relaxed/simple; bh=xXatcEbqRcdF6o15oAOgrUWiXRC+bXY+6S7fbGqNjYo=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=u4OteddJs/mvpoLl/BqRO0Q8ejmWYKBrAlpqjUrVZ8pZRtfHba956H9BNd89ZHWWIBqw2n8n6mC7VTvo5NHaohN9LM5uzec0fdzG6zqMIv/ELk3IjHDCyQSr2zRPcX0zlVpsqtNhLK0zC6iLLyMNFy9ZnKa4HuRIAERgO70OAaY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=Gc+dOGDz; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="Gc+dOGDz" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.2/8.18.1.2) with ESMTP id 57EMcS2E019295; Fri, 15 Aug 2025 08:34:45 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:message-id:mime-version :subject:to; s=pp1; bh=rZQsVqf8xi3ysOeGDpSQuniDLM2HRrESfrp+bbclf Lk=; b=Gc+dOGDzjxu6mT6n4Lvgge7+RT0XZP0IqX25ksAQRim9pzCXiMIUKJL7V rK4pKCL1RLiipNlavrhLuDshzELA8b+Fpow1uXPWqiZhTUjgjx7VP8lxx6KBMZtA KDlxklULiQeguPwBCqCmZim+EX7WfOMGBchkHISC2FoYJx9skyPhOMfV7Kg+GlpI T7f4l3o471SkZq+x7yRDDYwuagzuSDqQSvk4cG+geJWr+9AaDvHXFNs6s7r6rtQV T4d08azo2HJeGwRKc8VtqiSAEDsJ+t8HupCXEEF4y8V2FZ5x4CIktKgOUnTteor8 34/gpIPvvkBWsE0pgREktLYhcyTlw== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 48gypeggv9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Aug 2025 08:34:45 +0000 (GMT) Received: from m0356517.ppops.net (m0356517.ppops.net [127.0.0.1]) by pps.reinject (8.18.1.12/8.18.0.8) with ESMTP id 57F8Wqab030288; Fri, 15 Aug 2025 08:34:44 GMT Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 48gypeggv8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Aug 2025 08:34:44 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 57F6AEO3026345; Fri, 15 Aug 2025 08:34:43 GMT Received: from smtprelay06.fra02v.mail.ibm.com ([9.218.2.230]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 48eh21g9ub-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Aug 2025 08:34:43 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay06.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 57F8YddK20775218 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 15 Aug 2025 08:34:39 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 40EAD20040; Fri, 15 Aug 2025 08:34:39 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9EF3020043; Fri, 15 Aug 2025 08:34:32 +0000 (GMT) Received: from localhost.localdomain (unknown [9.61.240.145]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 15 Aug 2025 08:34:32 +0000 (GMT) From: Athira Rajeev To: acme@kernel.org, jolsa@kernel.org, adrian.hunter@intel.com, maddy@linux.ibm.com, irogers@google.com, namhyung@kernel.org Cc: linux-perf-users@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, aboorvad@linux.ibm.com, sshegde@linux.ibm.com, atrajeev@linux.ibm.com, kjain@linux.ibm.com, hbathini@linux.vnet.ibm.com, Aditya.Bodkhe1@ibm.com, venkat88@linux.ibm.com Subject: [PATCH 00/14] Add interface to expose vpa dtl counters via perf Date: Fri, 15 Aug 2025 14:03:53 +0530 Message-Id: <20250815083407.27953-1-atrajeev@linux.ibm.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=eaU9f6EH c=1 sm=1 tr=0 ts=689ef125 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=2OwXVqhp2XgA:10 a=lFXqBt1PEsZ4qluRa4AA:9 X-Proofpoint-GUID: v_BQv7jVt1Lklqg3JZ0aIl7XP1hD8sf6 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODEzMDE2NyBTYWx0ZWRfX/v8JnCbgJsdE THPO6QnT0YZUIDaxPuq832dL9p4vw5ZZ5JEIGvD7W0iUGrZayhoP7x95Mfp4ugqMomMjHyiZd4X 7qHmB7VREgF8rxl9WU/PYK9z8p11Z48NA79uzjDPAAqselMAmGto1NPAz0NtZu6FV2jm17+wR/Z lo9ulOVZLfW4l7PWAtbHtHfp9LyztYFz3GIyJLSOVKhxpoPsZb4zJ+Z97ULziIGjnxGxFEoNmqN J6U9V0nflmpJqX0uwzOeWGlm7QzC4AS4OmOkCmJlRbX0yiGEW6mSghXmaW0jWbKvHgCGmnX9wvY dPcG2uI1M2y+zhPmwCYdnciso2c8Ob7JnLgkSFs9agETDz+tcVHxwAwvTYmMzVlNLyYrn57cGpE OEHh4g1A X-Proofpoint-ORIG-GUID: B3vLzg2MrLDJ_yfecziR_pcBxbb54-kP X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-15_02,2025-08-14_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 clxscore=1011 priorityscore=1501 spamscore=0 bulkscore=0 malwarescore=0 adultscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508130167 The pseries Shared Processor Logical Partition(SPLPAR) machines can retrieve a log of dispatch and preempt events from the hypervisor using data from Disptach Trace Log(DTL) buffer. With this information, user can retrieve when and why each dispatch & preempt has occurred. The vpa-dtl PMU exposes the Virtual Processor Area(VPA) DTL counters via perf. - Patches 1 to 6 has powerpc PMU driver code changes to capture DTL trace in perf.data. And patch 14 has documentation update. - Patch 7 to 13 is perf tools side code changes to enable perf report/script on perf.data file Infrastructure used =================== The VPA DTL PMU counters do not interrupt on overflow or generate any PMI interrupts. Therefore, hrtimer is used to poll the DTL data. The timer nterval can be provided by user via sample_period field in nano seconds. vpa dtl pmu has one hrtimer added per vpa-dtl pmu thread. DTL (Dispatch Trace Log) contains information about dispatch/preempt, enqueue time etc. We directly copy the DTL buffer data as part of auxiliary buffer and it will be processed later. This will avoid time taken to create samples in the kernel space. The PMU driver collecting Dispatch Trace Log (DTL) entries makes use of AUX support in perf infrastructure. On the tools side, this data is made available as PERF_RECORD_AUXTRACE records. To corelate each DTL entry with other events across CPU's, an auxtrace_queue is created for each CPU. Each auxtrace queue has a array/list of auxtrace buffers. All auxtrace queues is maintained in auxtrace heap. The queues are sorted based on timestamp. When the different PERF_RECORD_XX records are processed, compare the timestamp of perf record with timestamp of top element in the auxtrace heap so that DTL events can be co-related with other events Process the auxtrace queue if the timestamp of element from heap is lower than timestamp from entry in perf record. Sometimes it could happen that one buffer is only partially processed. if the timestamp of occurrence of another event is more than currently processed element in the queue, it will move on to next perf record. So keep track of position of buffer to continue processing next time. Update the timestamp of the auxtrace heap with the timestamp of last processed entry from the auxtrace buffer. This infrastructure ensures dispatch trace log entries can be corelated and presented along with other events like sched. vpa-dtl PMU example usage # ls /sys/devices/vpa_dtl/ events format perf_event_mux_interval_ms power subsystem type uevent To capture the DTL data using perf record: # ./perf record -a -e sched:*,vpa_dtl/dtl_all/ -c 1000000000 sleep 1 The result can be interpreted using perf report. Snippet of perf report -D: # ./perf report -D There are different PERF_RECORD_XX records. In that records corresponding to auxtrace buffers includes: 1. PERF_RECORD_AUX Conveys that new data is available in AUX area 2. PERF_RECORD_AUXTRACE_INFO Describes offset and size of auxtrace data in the buffers 3. PERF_RECORD_AUXTRACE This is the record that defines the auxtrace data which here in case of vpa-dtl pmu is dispatch trace log data. Snippet from perf report -D showing the PERF_RECORD_AUXTRACE dump 0 0 0x39b10 [0x30]: PERF_RECORD_AUXTRACE size: 0x690 offset: 0 ref: 0 idx: 0 tid: -1 cpu: 0 . . ... VPA DTL PMU data: size 1680 bytes, entries is 35 . 00000000: boot_tb: 21349649546353231, tb_freq: 512000000 . 00000030: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:7064, ready_to_enqueue_time:187, waiting_to_ready_time:6611773 . 00000060: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:146, ready_to_enqueue_time:0, waiting_to_ready_time:15359437 . 00000090: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:4868, ready_to_enqueue_time:232, waiting_to_ready_time:5100709 . 000000c0: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:179, ready_to_enqueue_time:0, waiting_to_ready_time:30714243 . 000000f0: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:197, ready_to_enqueue_time:0, waiting_to_ready_time:15350648 . 00000120: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:213, ready_to_enqueue_time:0, waiting_to_ready_time:15353446 . 00000150: dispatch_reason:priv doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:212, ready_to_enqueue_time:0, waiting_to_ready_time:15355126 . 00000180: dispatch_reason:decrementer interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:6368, ready_to_enqueue_time:164, waiting_to_ready_time:5104665 Above is representation of dtl entry of below format: struct dtl_entry { u8 dispatch_reason; u8 preempt_reason; u16 processor_id; u32 enqueue_to_dispatch_time; u32 ready_to_enqueue_time; u32 waiting_to_ready_time; u64 timebase; u64 fault_addr; u64 srr0; u64 srr1; }; First two fields represent the dispatch reason and preempt reason. The post procecssing of PERF_RECORD_AUXTRACE records will translate to meaninful data for user to consume. Visualize the dispatch trace log entries with perf report: # ./perf record -a -e sched:*,vpa_dtl/dtl_all/ -c 1000000000 sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.300 MB perf.data ] # ./perf report # Samples: 321 of event 'vpa-dtl' # Event count (approx.): 321 # # Children Self Command Shared Object Symbol # ........ ........ ....... ................. .............................. # 100.00% 100.00% swapper [kernel.kallsyms] [k] plpar_hcall_norets_notrace Visualize the dispatch trace log entries with perf script: # ./perf script perf 13322 [002] 233.835807: sched:sched_switch: perf:13322 [120] R ==> migration/2:27 [0] migration/2 27 [002] 233.835811: sched:sched_migrate_task: comm=perf pid=13322 prio=120 orig_cpu=2 dest_cpu=3 migration/2 27 [002] 233.835818: sched:sched_stat_runtime: comm=migration/2 pid=27 runtime=9214 [ns] migration/2 27 [002] 233.835819: sched:sched_switch: migration/2:27 [0] S ==> swapper/2:0 [120] swapper 0 [002] 233.835822: vpa-dtl: timebase: 338954486062657 dispatch_reason:decrementer_interrupt, preempt_reason:H_CEDE, enqueue_to_dispatch_time:435, ready_to_enqueue_time:0, waiting_to_ready_time:34775058, processor_id: 202 c0000000000f8094 plpar_hcall_norets_notrace+0x18 ([kernel.kallsyms]) swapper 0 [001] 233.835886: vpa-dtl: timebase: 338954486095398 dispatch_reason:priv_doorbell, preempt_reason:H_CEDE, enqueue_to_dispatch_time:542, ready_to_enqueue_time:0, waiting_to_ready_time:1245360, processor_id: 201 c0000000000f8094 plpar_hcall_norets_notrace+0x18 ([kernel.kallsyms]) Aboorva Devarajan (1): powerpc/time: Expose boot_tb via accessor Athira Rajeev (11): powerpc/perf/vpa-dtl: Add support to setup and free aux buffer for capturing DTL data powerpc/perf/vpa-dtl: Add support to capture DTL data in aux buffer powerpc/perf/vpa-dtl: Handle the writing of perf record when aux wake up is needed tools/perf: Add basic CONFIG_AUXTRACE support for VPA pmu on powerpc tools/perf: process auxtrace events and display in perf report -D tools/perf: Add event name as vpa-dtl of PERF_TYPE_SYNTH type to present DTL samples tools/perf: Allocate and setup aux buffer queue to help co-relate with other events across CPU's tools/perf: Process the DTL entries in queue and deliver samples tools/perf: Add support for printing synth event details via default callback tools/perf: Enable perf script to present the DTL entries powerpc/perf/vpa-dtl: Add documentation for VPA dispatch trace log PMU Kajol Jain (2): powerpc/vpa_dtl: Add interface to expose vpa dtl counters via perf docs: ABI: sysfs-bus-event_source-devices-vpa-dtl: Document sysfs event format entries for vpa_dtl pmu .../sysfs-bus-event_source-devices-vpa-dtl | 25 + Documentation/arch/powerpc/index.rst | 1 + Documentation/arch/powerpc/vpa-dtl.rst | 155 ++++ arch/powerpc/include/asm/time.h | 2 + arch/powerpc/kernel/time.c | 7 +- arch/powerpc/perf/Makefile | 2 +- arch/powerpc/perf/vpa-dtl.c | 605 ++++++++++++++ tools/perf/arch/powerpc/util/Build | 1 + tools/perf/arch/powerpc/util/auxtrace.c | 122 +++ tools/perf/builtin-script.c | 26 + tools/perf/util/Build | 1 + tools/perf/util/auxtrace.c | 4 + tools/perf/util/auxtrace.h | 1 + tools/perf/util/event.h | 1 + tools/perf/util/powerpc-vpadtl.c | 756 ++++++++++++++++++ tools/perf/util/powerpc-vpadtl.h | 45 ++ 16 files changed, 1752 insertions(+), 2 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-event_source-devices-vpa-dtl create mode 100644 Documentation/arch/powerpc/vpa-dtl.rst create mode 100644 arch/powerpc/perf/vpa-dtl.c create mode 100644 tools/perf/arch/powerpc/util/auxtrace.c create mode 100644 tools/perf/util/powerpc-vpadtl.c create mode 100644 tools/perf/util/powerpc-vpadtl.h -- 2.47.1