Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422756AbbD2JJ5 (ORCPT ); Wed, 29 Apr 2015 05:09:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:41152 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031610AbbD2JJy (ORCPT ); Wed, 29 Apr 2015 05:09:54 -0400 Date: Wed, 29 Apr 2015 11:09:41 +0200 From: Peter Zijlstra To: Andy Lutomirski Cc: Len Brown , "linux-kernel@vger.kernel.org" , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo Subject: Re: [RFC] x86, perf: Add an aperfmperf driver Message-ID: <20150429090941.GO5029@twins.programming.kicks-ass.net> References: <2c37309d20afadf88ad4a82cf0ce02b9152801e2.1430256154.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2c37309d20afadf88ad4a82cf0ce02b9152801e2.1430256154.git.luto@kernel.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2607 Lines: 78 On Tue, Apr 28, 2015 at 02:25:37PM -0700, Andy Lutomirski wrote: > diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile > index 80091ae54c2b..fadc822efc90 100644 > --- a/arch/x86/kernel/cpu/Makefile > +++ b/arch/x86/kernel/cpu/Makefile > @@ -45,6 +45,8 @@ obj-$(CONFIG_PERF_EVENTS_INTEL_UNCORE) += perf_event_intel_uncore.o \ > perf_event_intel_uncore_snb.o \ > perf_event_intel_uncore_snbep.o \ > perf_event_intel_uncore_nhmex.o > +obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_aperf_mperf.o > +obj-$(CONFIG_CPU_SUP_AMD) += perf_event_aperf_mperf.o Does this actually work? I would expect it to go complain about having to build it twice if you have both set. > diff --git a/arch/x86/kernel/cpu/perf_event_aperfmperf.c b/arch/x86/kernel/cpu/perf_event_aperfmperf.c > new file mode 100644 > index 000000000000..6e6d113bd9ce > --- /dev/null > +++ b/arch/x86/kernel/cpu/perf_event_aperfmperf.c > @@ -0,0 +1,119 @@ > +#include > + > +#define APERFMPERF_EVENT_APERF 0 > +#define APERFMPERF_EVENT_MPERF 1 > + > +static int aperfmperf_event_init(struct perf_event *event) > +{ > + if (event->attr.type != event->pmu->type) > + return -ENOENT; > + > + if (event->attr.config != APERFMPERF_EVENT_APERF && > + event->attr.config != APERFMPERF_EVENT_MPERF) > + return -ENOENT; Once we pass the type test we know its 'our' event, and we can go return fatal errors. No other PMU will pick this up. This could therefore turn into an -EINVAL. > + > + if (event->attr.config1 != 0) > + return -ENOENT; Idem. > + /* no sampling */ > + if (event->hw.sample_period) > + return -EINVAL; You could have set pmu::capabilities = PERF_PMU_CAP_NO_INTERRUPT which would also have killed that dead. > + /* unsupported modes and filters */ > + if (event->attr.exclude_user || > + event->attr.exclude_kernel || > + event->attr.exclude_hv || > + event->attr.exclude_idle || > + event->attr.exclude_host || > + event->attr.exclude_guest || > + event->attr.freq || > + event->attr.sample_period) /* no sampling */ > + return -EINVAL; > + > + event->hw.idx = -1; > + event->hw.event_base = (event->attr.config == APERFMPERF_EVENT_APERF ? > + MSR_IA32_APERF : MSR_IA32_MPERF); > + > + return 0; > +} The rest looks about right. Very simple thing indeed ;-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/