From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BA458C433DF for ; Fri, 3 Jul 2020 11:00:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9344020936 for ; Fri, 3 Jul 2020 11:00:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KuKWwJVw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726289AbgGCLA4 (ORCPT ); Fri, 3 Jul 2020 07:00:56 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:39302 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725915AbgGCLA4 (ORCPT ); Fri, 3 Jul 2020 07:00:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593774053; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=vCwNwIJLk7+4g1qLA90x2U92e+ugEUwZVEI97T0FP7M=; b=KuKWwJVwgivU6vm2j5UQizq8L6b2nhAVVMPcmX3NtmJ44yeWK0RIX8KM0kOeoKwX+fVXV3 m4J83OYOR/2jsYkO/+nLaemyoOQzqfJI2g8IrWnsNI2NuNlEMpUYMm4nHCSHC5wH+Kv12B l/peo3UzNigKxdkCz3Xps/VUQW7rMcM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-363-DP4n7I3QNvWyx4p150F86w-1; Fri, 03 Jul 2020 07:00:47 -0400 X-MC-Unique: DP4n7I3QNvWyx4p150F86w-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED094804002; Fri, 3 Jul 2020 11:00:45 +0000 (UTC) Received: from krava (unknown [10.40.194.24]) by smtp.corp.redhat.com (Postfix) with SMTP id 060A52DE76; Fri, 3 Jul 2020 11:00:42 +0000 (UTC) Date: Fri, 3 Jul 2020 13:00:42 +0200 From: Jiri Olsa To: Jin Yao Cc: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, irogers@google.com, Adrian Hunter Subject: Re: [PATCH] perf evsel: Don't set sample_regs_intr/sample_regs_user for dummy event Message-ID: <20200703110042.GA3282312@krava> References: <20200703004215.24418-1-yao.jin@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200703004215.24418-1-yao.jin@linux.intel.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 03, 2020 at 08:42:15AM +0800, Jin Yao wrote: > Since commit 0a892c1c9472 ("perf record: Add dummy event during system wide synthesis"), > a dummy event is added to capture mmaps. > > But if we run perf-record as, > > # perf record -e cycles:p -IXMM0 -a -- sleep 1 > Error: > dummy:HG: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' > > The issue is, if we enable the extended regs (-IXMM0), but the > pmu->capabilities is not set with PERF_PMU_CAP_EXTENDED_REGS, the kernel > will return -EOPNOTSUPP error. > > See following code pieces. > > /* in kernel/events/core.c */ > static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) > > { > .... > if (!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_REGS) && > has_extended_regs(event)) > ret = -EOPNOTSUPP; > .... > } > > For software dummy event, the PMU should be not set with > PERF_PMU_CAP_EXTENDED_REGS. But unfortunately in current code, the dummy > event has possibility to be set with PERF_REG_EXTENDED_MASK bit. > > In evsel__config, /* tools/perf/util/evsel.c */ > > if (opts->sample_intr_regs) { > attr->sample_regs_intr = opts->sample_intr_regs; > } > > If we use -IXMM0, the attr>sample_regs_intr will be set with > PERF_REG_EXTENDED_MASK bit. > > It doesn't make sense to set attr->sample_regs_intr for a > software dummy event. > > This patch adds dummy event checking before setting > attr->sample_regs_intr. > > After: > # ./perf record -e cycles:p -IXMM0 -a -- sleep 1 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.413 MB perf.data (45 samples) ] LGTM, Adrian (cc-ed) just added another check to the same place, but it looks like both of them should be there: https://lore.kernel.org/lkml/20200630133935.11150-2-adrian.hunter@intel.com/ jirka > > Fixes: 0a892c1c9472 ("perf record: Add dummy event during system wide synthesis") > Signed-off-by: Jin Yao > --- > tools/perf/util/evsel.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c > index 96e5171dce41..df3315543e86 100644 > --- a/tools/perf/util/evsel.c > +++ b/tools/perf/util/evsel.c > @@ -1020,12 +1020,12 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts, > if (callchain && callchain->enabled && !evsel->no_aux_samples) > evsel__config_callchain(evsel, opts, callchain); > > - if (opts->sample_intr_regs) { > + if (opts->sample_intr_regs && !is_dummy_event(evsel)) { > attr->sample_regs_intr = opts->sample_intr_regs; > evsel__set_sample_bit(evsel, REGS_INTR); > } > > - if (opts->sample_user_regs) { > + if (opts->sample_user_regs && !is_dummy_event(evsel)) { > attr->sample_regs_user |= opts->sample_user_regs; > evsel__set_sample_bit(evsel, REGS_USER); > } > -- > 2.17.1 >