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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 01EFCC433E0 for ; Mon, 10 Aug 2020 18:11:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5AE320838 for ; Mon, 10 Aug 2020 18:11:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597083098; bh=g/t91faDycY4mseqjHu9BMl29MuRrgmwUh+bEg6Hgsg=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=ou6TgHLU0t+0BZUJrJWebd/gRr1GYrI6+PW5bh6vX6TyKLfzOxW6oPC9n0sWgcKUb KRubShyi+5vw1IdgmEMrVsK2jg1zBZjqg3cGaEQB2MTBHWnQqRVs5wK3EYCwvvMYaG +vOIcIXvzS2TlMI4Tr0/6Wz2110ICOMyn8Pf5NP4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728111AbgHJSLh (ORCPT ); Mon, 10 Aug 2020 14:11:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:51886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727972AbgHJSLg (ORCPT ); Mon, 10 Aug 2020 14:11:36 -0400 Received: from mail-ot1-f52.google.com (mail-ot1-f52.google.com [209.85.210.52]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0184220838 for ; Mon, 10 Aug 2020 18:11:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597083096; bh=g/t91faDycY4mseqjHu9BMl29MuRrgmwUh+bEg6Hgsg=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=spkSqZBpZi71Ys9ESVPWib9QM4a0+dUXn8Lcfqpqglpbs4m3Y2UCV5kdVpl+y9WFi F8EmYeN7eiWwiIXOanNvMDkHZIBZAWoQJ7AkWKzh/A7IPBGW6pLT7VMNIfvgAM/vvF Mh2Yzj0GVGlJ/NOBZQK5/wsgHdONLJgdNsHDylPE= Received: by mail-ot1-f52.google.com with SMTP id v6so8002942ota.13 for ; Mon, 10 Aug 2020 11:11:35 -0700 (PDT) X-Gm-Message-State: AOAM533itX/x4tLjlebKw6mAv/4zwXt04+X5GowpleFyubF+6coKpGTE Bhu3WUmVyaas4qY4tonjKK+rTXTr5ViLhmk+YA== X-Google-Smtp-Source: ABdhPJyIcpMR1q6VzAeE/qkvttTnUF6tMclUZpugrbOgbjhBSTkQcM3zw3f5rc5dQEF2DOUXdRFuMPxOcEW5p+HQ2VQ= X-Received: by 2002:a9d:7f84:: with SMTP id t4mr1798410otp.192.1597083095312; Mon, 10 Aug 2020 11:11:35 -0700 (PDT) MIME-Version: 1.0 References: <20200807230517.57114-1-robh@kernel.org> <20200808102208.GA619980@krava> In-Reply-To: <20200808102208.GA619980@krava> From: Rob Herring Date: Mon, 10 Aug 2020 12:11:23 -0600 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC] libperf: Add support for user space counter access To: Jiri Olsa Cc: "linux-kernel@vger.kernel.org" , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 8, 2020 at 4:22 AM Jiri Olsa wrote: > > On Fri, Aug 07, 2020 at 05:05:17PM -0600, Rob Herring wrote: > > x86 and arm64 can both support direct access of event counters in > > userspace. The access sequence is less than trivial and currently exists > > in perf test code (tools/perf/arch/x86/tests/rdpmc.c) with copies in > > projects such as PAPI and libpfm4. > > > > Patches to add arm64 userspace support are pending[1]. > > > > For this RFC, looking for a yes, seems like a good idea, or no, go away we > > don't want this in libperf. > > hi, > looks great! > > I wanted to add this for very long time.. so yes, we want this ;-) Thanks for the quick feedback. Would this be better implemented as a fast path for perf_evsel__read()? If so, how to get the mmap data which is associated with a evlist rather than a evsel? Rob