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Fri, 24 Jul 2020 09:07:41 -0700 (PDT) Subject: Re: [PATCH V7 08/14] perf/x86/intel: Generic support for hardware TopDown metrics To: peterz@infradead.org Cc: acme@redhat.com, mingo@kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, eranian@google.com, alexander.shishkin@linux.intel.com, ak@linux.intel.com, like.xu@linux.intel.com References: <20200723171117.9918-1-kan.liang@linux.intel.com> <20200723171117.9918-9-kan.liang@linux.intel.com> <20200724131906.GW119549@hirez.programming.kicks-ass.net> <20200724152755.GK43129@hirez.programming.kicks-ass.net> From: "Liang, Kan" Message-ID: Date: Fri, 24 Jul 2020 12:07:40 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200724152755.GK43129@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/24/2020 11:27 AM, peterz@infradead.org wrote: > On Fri, Jul 24, 2020 at 03:19:06PM +0200, peterz@infradead.org wrote: >> On Thu, Jul 23, 2020 at 10:11:11AM -0700, kan.liang@linux.intel.com wrote: >>> @@ -3375,6 +3428,72 @@ static int intel_pmu_hw_config(struct perf_event *event) >>> if (event->attr.type != PERF_TYPE_RAW) >>> return 0; >>> >>> + /* >>> + * Config Topdown slots and metric events >>> + * >>> + * The slots event on Fixed Counter 3 can support sampling, >>> + * which will be handled normally in x86_perf_event_update(). >>> + * >>> + * The metric events don't support sampling. >>> + * >>> + * For counting, topdown slots and metric events will be >>> + * handled specially for event update. >>> + * A flag PERF_X86_EVENT_TOPDOWN is applied for the case. >>> + */ >>> + if (x86_pmu.intel_cap.perf_metrics && is_topdown_event(event)) { >>> + if (is_metric_event(event)) { >>> + struct perf_event *leader = event->group_leader; >>> + struct perf_event *sibling; >>> + >>> + /* The metric events don't support sampling. */ >>> + if (is_sampling_event(event)) >>> + return -EINVAL; >>> + >>> + /* The metric events cannot be a group leader. */ >>> + if (leader == event) >>> + return -EINVAL; >>> + >>> + /* >>> + * The slots event cannot be the leader of a topdown >>> + * sample-read group, e.g., {slots, topdown-retiring}:S >>> + */ >>> + if (is_slots_event(leader) && is_sampling_event(leader)) >>> + return -EINVAL; >> >> This has nothing to do with sample-read; SLOTS cannot be sampling when >> coupled with the METRIC stuff because hardware is daft. >> >> And you can have SAMPLE_READ on non-leader events just fine. >> >>> + >>> + /* >>> + * The slots event must be before the metric events, >>> + * because we only update the values of a topdown >>> + * group once with the slots event. >>> + */ >>> + if (!is_slots_event(leader)) { >>> + for_each_sibling_event(sibling, leader) { >>> + if (is_slots_event(sibling)) >>> + break; >>> + if (is_metric_event(sibling)) >>> + return -EINVAL; >>> + } >>> + } >> >> Per the SIBLING patch this then wants to be: >> >> if (!is_slots_event(leader)) >> return -EINVAL; >> >> event->event_caps |= PERF_EV_CAP_SIBLING. >> /* >> * Only once we have a METRICs sibling to we >> * need TopDown magic. >> */ >> leader->hw.flags |= PERF_X86_EVENT_TOPDOWN; >>> + } >>> + >>> + if (!is_sampling_event(event)) { >>> + if (event->attr.config1 != 0) >>> + return -EINVAL; >> >> How does this depend on sampling? >> >>> + /* >>> + * The TopDown metrics events and slots event don't >>> + * support any filters. >>> + */ >>> + if (event->attr.config & X86_ALL_EVENT_FLAGS) >>> + return -EINVAL; >> >> That seems independent of sampling too. Even a sampling SLOTS shouldn't >> be having any of those afaict. >> >>> + >>> + event->hw.flags |= PERF_X86_EVENT_TOPDOWN; >> >> This is confusing too, a !sampling SLOTS event without METRIC siblings >> shouldn't have this set, right? So arguably, this should be like above. >> >>> + >>> + event->event_caps |= PERF_EV_CAP_COEXIST; >>> + >>> + if (is_metric_event(event)) >>> + event->hw.flags &= ~PERF_X86_EVENT_RDPMC_ALLOWED; >> >> This too seems like something that should be in the is_metric_event() >> branch above. >> >>> + } >>> + } >>> + >>> if (!(event->attr.config & ARCH_PERFMON_EVENTSEL_ANY)) >>> return 0; >>> > > FWIW, I pushed out a branch with all these changes in: > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/metric > > Just to get it some build love, if you want it differently, I'm happy to > throw it all out again. Thanks Peter. I will pull the branch and do more tests. Thanks, Kan