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Wed, 27 Aug 2025 05:27:01 GMT Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6821520049; Wed, 27 Aug 2025 05:27:01 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A772520040; Wed, 27 Aug 2025 05:27:00 +0000 (GMT) Received: from [9.152.212.92] (unknown [9.152.212.92]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 27 Aug 2025 05:27:00 +0000 (GMT) Message-ID: Date: Wed, 27 Aug 2025 07:27:00 +0200 Precedence: bulk X-Mailing-List: sparclinux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 18/19] perf: Introduce positive capability for raw events To: Mark Rutland , Robin Murphy , Sumanth Korikkar , Jan Polensky Cc: peterz@infradead.org, mingo@redhat.com, will@kernel.org, acme@kernel.org, namhyung@kernel.org, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, imx@lists.linux.dev, linux-csky@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-pm@vger.kernel.org, linux-rockchip@lists.infradead.org, dmaengine@vger.kernel.org, linux-fpga@vger.kernel.org, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, coresight@lists.linaro.org, iommu@lists.linux.dev, linux-amlogic@lists.infradead.org, linux-cxl@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-riscv@lists.infradead.org References: <542787fd188ea15ef41c53d557989c962ed44771.1755096883.git.robin.murphy@arm.com> Content-Language: en-US From: Thomas Richter Organization: IBM In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAxMCBTYWx0ZWRfXx7bT3ieVYWZ1 FvRIJn/6odyl76gPtjq2fdUI3+ddgoyBguazv17xAc0h1PWPsciO7Io1+yf38004HJX48EZKQe4 jjqa2jsZ613Il7PEWWZLmHVXl0DVElauSgaXsW2jrn5unNTZZAgCkgP5ixkSnbssGkUA98RWoHK 6CllyViFj8nmb4/kmZamtgDzlo/xirMdIPTqK1ytIy748E4TyQcONzfTAVM6cDoHbAMLdYuTHtD UT6EmBwE8Tz6Ajw1M3OeNTbMk21jMwITf/ouwlMB6Q/Hm12FuudC6E2iwfSIPWm8nU5cvD4JBmw ghpRUxLnbbdBrU5mCsCpBm2H2yjaVRWCqCxRNsBxe1xCwhV1Oev6PUoPQ5TLoGumXLZUFEfuXwo /BJHYr+T X-Proofpoint-ORIG-GUID: Z1OBCqtS81HxjTSNcENNGRKeOQ0QzPO9 X-Proofpoint-GUID: 4pnWswYamnTcgbcPVqCp3LQWR1ph9h16 X-Authority-Analysis: v=2.4 cv=evffzppX c=1 sm=1 tr=0 ts=68ae972b cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=2OwXVqhp2XgA:10 a=7CQSdrXTAAAA:8 a=KByoUL483hSIROooWq4A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=a-qgeE7W1pNrGK8U0ZQC:22 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=2025-08-26_02,2025-08-26_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 bulkscore=0 impostorscore=0 clxscore=1015 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508230010 On 8/26/25 15:43, Mark Rutland wrote: > On Wed, Aug 13, 2025 at 06:01:10PM +0100, Robin Murphy wrote: >> Only a handful of CPU PMUs accept PERF_TYPE_{RAW,HARDWARE,HW_CACHE} >> events without registering themselves as PERF_TYPE_RAW in the first >> place. Add an explicit opt-in for these special cases, so that we can >> make life easier for every other driver (and probably also speed up the >> slow-path search) by having perf_try_init_event() do the basic type >> checking to cover the majority of cases. >> >> Signed-off-by: Robin Murphy > > > To bikeshed a little here, I'm not keen on the PERF_PMU_CAP_RAW_EVENTS > name, because it's not clear what "RAW" really means, and people will > definitely read that to mean something else. > > Could we go with something like PERF_PMU_CAP_COMMON_CPU_EVENTS, to make > it clear that this is about opting into CPU-PMU specific event types (of > which PERF_TYPE_RAW is one of)? > > Likewise, s/is_raw_pmu()/pmu_supports_common_cpu_events()/. > >> --- >> >> A further possibility is to automatically add the cap to PERF_TYPE_RAW >> PMUs in perf_pmu_register() to have a single point-of-use condition; I'm >> undecided... > > I reckon we don't need to automagically do that, but I reckon that > is_raw_pmu()/pmu_supports_common_cpu_events() should only check the cap, > and we don't read anything special into any of > PERF_TYPE_{RAW,HARDWARE,HW_CACHE}. > >> --- >> arch/s390/kernel/perf_cpum_cf.c | 1 + >> arch/s390/kernel/perf_pai_crypto.c | 2 +- >> arch/s390/kernel/perf_pai_ext.c | 2 +- >> arch/x86/events/core.c | 2 +- >> drivers/perf/arm_pmu.c | 1 + >> include/linux/perf_event.h | 1 + >> kernel/events/core.c | 15 +++++++++++++++ >> 7 files changed, 21 insertions(+), 3 deletions(-) >> >> diff --git a/arch/s390/kernel/perf_cpum_cf.c b/arch/s390/kernel/perf_cpum_cf.c >> index 1a94e0944bc5..782ab755ddd4 100644 >> --- a/arch/s390/kernel/perf_cpum_cf.c >> +++ b/arch/s390/kernel/perf_cpum_cf.c >> @@ -1054,6 +1054,7 @@ static void cpumf_pmu_del(struct perf_event *event, int flags) >> /* Performance monitoring unit for s390x */ >> static struct pmu cpumf_pmu = { >> .task_ctx_nr = perf_sw_context, >> + .capabilities = PERF_PMU_CAP_RAW_EVENTS, >> .pmu_enable = cpumf_pmu_enable, >> .pmu_disable = cpumf_pmu_disable, >> .event_init = cpumf_pmu_event_init, > > Tangential, but use of perf_sw_context here looks bogus. > It might look strange, but it was done on purpose. For details see commit 9254e70c4ef1 ("s390/cpum_cf: use perf software context for hardware counters") Background was a WARN_ON() statement which fired, because several PMU device drivers existed in parallel on s390x platform. Not sure if this condition is still true after all these years... -- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Geschäftsführung: David Faller Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294