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=-11.3 required=3.0 tests=BAYES_00,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 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 C73CAC4363D for ; Tue, 22 Sep 2020 18:33:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7ADA52065D for ; Tue, 22 Sep 2020 18:33:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RlX9qRnw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726703AbgIVSdB (ORCPT ); Tue, 22 Sep 2020 14:33:01 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:48797 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbgIVSdA (ORCPT ); Tue, 22 Sep 2020 14:33:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600799579; 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=WwPXGhPL6xp8ZNIQx0i7iF/a9jrzbtF5yWzgU61LP9c=; b=RlX9qRnwHgCkTACGivUUsXZJpF55Mqm3jM/ZzVBdilTYuzHEbp2yfUzrI1ui83pcfCqfJW y/Lxv22JaLeL9Sac8VE/ry+d4IsriUjfMZ9LCsgVHYSvk1v8I69n5nQEuCo42oaWfUQhBX OlBx85wbV4Ay6fn/+SoySLQqCISSKOU= 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-490-zk5tI3t-M2SXEF54OEKlUQ-1; Tue, 22 Sep 2020 14:32:55 -0400 X-MC-Unique: zk5tI3t-M2SXEF54OEKlUQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 456661017DC5; Tue, 22 Sep 2020 18:32:53 +0000 (UTC) Received: from krava (ovpn-112-28.ams2.redhat.com [10.36.112.28]) by smtp.corp.redhat.com (Postfix) with SMTP id F2F3578805; Tue, 22 Sep 2020 18:32:49 +0000 (UTC) Date: Tue, 22 Sep 2020 20:32:49 +0200 From: Jiri Olsa To: Rob Herring Cc: Will Deacon , Catalin Marinas , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , "linux-kernel@vger.kernel.org" , linux-arm-kernel , Alexander Shishkin , Namhyung Kim , Raphael Gault , Mark Rutland , Jonathan Cameron , Ian Rogers , Honnappa Nagarahalli Subject: Re: [PATCH v3 05/10] libperf: Add libperf_evsel__mmap() Message-ID: <20200922183249.GA2718767@krava> References: <20200911215118.2887710-1-robh@kernel.org> <20200911215118.2887710-6-robh@kernel.org> <20200918143331.GF2626435@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 22, 2020 at 09:28:44AM -0600, Rob Herring wrote: > On Fri, Sep 18, 2020 at 8:33 AM Jiri Olsa wrote: > > > > On Fri, Sep 11, 2020 at 03:51:13PM -0600, Rob Herring wrote: > > > In order to support usersapce access, an event must be mmapped. While > > > there's already mmap support for evlist, the usecase is a bit different > > > than the self monitoring with userspace access. So let's add a new > > > perf_evsel__mmap() function to mmap an evsel. This allows implementing > > > userspace access as a fastpath for perf_evsel__read(). > > > > > > The mmapped address is returned by perf_evsel__mmap() primarily for > > > users/tests to check if userspace access is enabled. > > > > > > Signed-off-by: Rob Herring > > > --- > > > v3: > > > - New patch split out from user access patch > > > --- > > > tools/lib/perf/Documentation/libperf.txt | 1 + > > > tools/lib/perf/evsel.c | 31 ++++++++++++++++++++++++ > > > tools/lib/perf/include/internal/evsel.h | 2 ++ > > > tools/lib/perf/include/perf/evsel.h | 2 ++ > > > tools/lib/perf/libperf.map | 1 + > > > 5 files changed, 37 insertions(+) > > > > > > diff --git a/tools/lib/perf/Documentation/libperf.txt b/tools/lib/perf/Documentation/libperf.txt > > > index 0c74c30ed23a..0b4694ce42b9 100644 > > > --- a/tools/lib/perf/Documentation/libperf.txt > > > +++ b/tools/lib/perf/Documentation/libperf.txt > > > @@ -136,6 +136,7 @@ SYNOPSIS > > > struct perf_thread_map *threads); > > > void perf_evsel__close(struct perf_evsel *evsel); > > > void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu); > > > + void *perf_evsel__mmap(struct perf_evsel *evsel, size_t length); > > > int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread, > > > struct perf_counts_values *count); > > > int perf_evsel__enable(struct perf_evsel *evsel); > > > diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c > > > index 4dc06289f4c7..99fa53dc0887 100644 > > > --- a/tools/lib/perf/evsel.c > > > +++ b/tools/lib/perf/evsel.c > > > @@ -11,10 +11,12 @@ > > > #include > > > #include > > > #include > > > +#include > > > #include > > > #include > > > #include > > > #include > > > +#include > > > > > > void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr) > > > { > > > @@ -156,6 +158,35 @@ void perf_evsel__close_cpu(struct perf_evsel *evsel, int cpu) > > > perf_evsel__close_fd_cpu(evsel, cpu); > > > } > > > > > > +void *perf_evsel__mmap(struct perf_evsel *evsel, size_t length) > > > +{ > > > > could you rather use 'int pages' insted of length as we > > do in perf_evlist__mmap, so we keep the same interface > > > > len = (pages + 1) * page_size > > Sure, but what's the reason it is pages minus 1? It seems a bit odd to > pass in 0 here to get 1 page which would be the typical usage. the user mmap page is extra, so when you map 2 pages you actualy map 3, but we want the size of what's available for storing events in the API jirka