From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 436E9208D7; Tue, 3 Oct 2023 11:00:38 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC2B8AC; Tue, 3 Oct 2023 04:00:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=934M3M5cJg5fSPGaIg7428I8uQBQncWaQiT8PHBnuSE=; b=E7a738Qf1E4DMNUqfeslJzFl/i WOWmTL94prinRHALF/qMyMN09I9RpJ7x8T7Xdypumf8nd85DI68BeVaeIbFQMWYY0QIA0hP54VVOU rLzlieEhIW4OD55KsQwYalA84ZCe/Poq/H3Xvj0rcY8QHD5wfNeprAkQMoP2qV8lYhgpXiTDartTi OZax6sqtjgVS9ZNFFqXdDoy77t80atP/Rt6RD5Vpa/Bb2bE2V39NbtcJ+c+vZF1PywRqu4W1jluuW bOCKowaJEQDGQiWk9uMEy5M+AjkTf/sOepm2xvr+adHjkQSi0NybO1hKCi6KjtUhwM3VGgTPIFtj1 K0tomjag==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qnd8U-00Ec4p-IJ; Tue, 03 Oct 2023 11:00:18 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 30FA6300665; Tue, 3 Oct 2023 13:00:18 +0200 (CEST) Date: Tue, 3 Oct 2023 13:00:18 +0200 From: Peter Zijlstra To: Tero Kristo Cc: x86@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, tglx@linutronix.de, hpa@zytor.com, irogers@google.com, jolsa@kernel.org, namhyung@kernel.org, adrian.hunter@intel.com, acme@kernel.org, mingo@redhat.com, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, alexander.shishkin@linux.intel.com, linux-perf-users@vger.kernel.org, mark.rutland@arm.com Subject: Re: [PATCHv2 2/2] perf/core: Allow reading package events from perf_event_read_local Message-ID: <20231003110018.GG27267@noisy.programming.kicks-ass.net> References: <20230912124432.3616761-2-tero.kristo@linux.intel.com> <20230913125956.3652667-1-tero.kristo@linux.intel.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230913125956.3652667-1-tero.kristo@linux.intel.com> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Wed, Sep 13, 2023 at 03:59:56PM +0300, Tero Kristo wrote: > Per-package perf events are typically registered with a single CPU only, > however they can be read across all the CPUs within the package. > Currently perf_event_read maps the event CPU according to the topology > information to avoid an unnecessary SMP call, however > perf_event_read_local deals with hard values and rejects a read with a > failure if the CPU is not the one exactly registered. Allow similar > mapping within the perf_event_read_local if the perf event in question > can support this. > > This allows users like BPF code to read the package perf events properly > across different CPUs within a package. > > Signed-off-by: Tero Kristo > --- > v2: > * prevent illegal array access in case event->oncpu == -1 > * split the event->cpu / event->oncpu handling to their own variables > > kernel/events/core.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 4c72a41f11af..6b343bac0a71 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -4425,6 +4425,9 @@ static int __perf_event_read_cpu(struct perf_event *event, int event_cpu) > { > u16 local_pkg, event_pkg; > > + if (event_cpu < 0 || event_cpu >= nr_cpu_ids) > + return event_cpu; if ((unsigned)event_cpu >= nr_cpu_ids) return event_cpu; As you could also find at the current __perf_event_read_cpu() callsite. > + > if (event->group_caps & PERF_EV_CAP_READ_ACTIVE_PKG) { > int local_cpu = smp_processor_id(); > > @@ -4528,6 +4531,8 @@ int perf_event_read_local(struct perf_event *event, u64 *value, > { > unsigned long flags; > int ret = 0; > + int event_cpu; > + int event_oncpu; You wrecked the x-mas tree :-) I'll fix both up. Thanks!