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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 06AEDC3A5A8 for ; Wed, 4 Sep 2019 17:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1987208E4 for ; Wed, 4 Sep 2019 17:53:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Upi8+Aiv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732481AbfIDRxw (ORCPT ); Wed, 4 Sep 2019 13:53:52 -0400 Received: from mail-lf1-f67.google.com ([209.85.167.67]:43539 "EHLO mail-lf1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732423AbfIDRxv (ORCPT ); Wed, 4 Sep 2019 13:53:51 -0400 Received: by mail-lf1-f67.google.com with SMTP id q27so16616884lfo.10 for ; Wed, 04 Sep 2019 10:53:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=VVuxddaCHhflkbZBXFm+YhEQBdKEAZG3dSIz77MNLHY=; b=Upi8+AivAt37q4HoCsU8AGx9KkLPpDqZigfbhcMCSsUPnnLIFN1mj+nTKYsjuL/pXL F4xbILdBb2zf4SPo3ummceM6zBpN3c/BDqg8+XoPcJDk91mbV8U7zzZKRLJCTTWKFdN6 eGcm2F/VYmzFnJKrzFpEwFU9C//AzRySaxyNzDXTpE1KeOQVotT5V+NGG0mcoqZrs5uF Mt57goHvTd/Pkmi1Y/hc/HtdKbWivFU1ZqYgl7ccYB3X+cMsoKaINpBr4xZByHm9ZTJs kDknNrasUuyTUrMylcWszQvl2BbhtvYBsAAjVCta5JvlDKuH0CKbEzWnUFf458+hk6QH eNeg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=VVuxddaCHhflkbZBXFm+YhEQBdKEAZG3dSIz77MNLHY=; b=DE3Tk2yiJ8JBWRUz0Ho0luqbFkc+Wq0Q9YCKv/TxM9D23d2FA7NsCruRccgGhMb79I jWwbRCkfNh+Vkol4PLGRXCVUjXYwkXuHO/xDkO3vsoPc2E16C/fsEsGqLkewt29is/ao zRQ929mV/lSVsMz1t9jbeobZNEOpOCSpyaT2ktcEgJtg22m4CaGfAb3GCw8EEXFyWzEZ gL3D5elYLSVJpDxS3bNHZFmLAZ58J+DvCQSqmgpvj5V/thtzoi1rVR8c8l5t5lKNxH52 GIhA/VkfMJwsxbWWNC194ifDyXT1E7a9Zxawh7799he5iHUXJb/gTnpKHiaCXzfK+SNE B9XA== X-Gm-Message-State: APjAAAXb7qcdyuKD06FQAVXHWCjcDT5F5dj5Y702RraJPcBqX+rPwest zAFt2bpYTzPS4cnrhJaXJYV0g77eiZ2RA6l95BI= X-Google-Smtp-Source: APXvYqxI7RDEom+xW8WF2r7OfFUfir8RHeU3Z/r/nPNAUp5MmKDRDBfEykuBTHwRnkxZ7cX01/ZUzlEBsGFd878r/G4= X-Received: by 2002:ac2:558a:: with SMTP id v10mr3468562lfg.162.1567619629528; Wed, 04 Sep 2019 10:53:49 -0700 (PDT) MIME-Version: 1.0 References: <20190903154340.860299-1-rkrcmar@redhat.com> <20190903154340.860299-3-rkrcmar@redhat.com> <20190904042310.GA159235@google.com> <20190904104332.ogsjtbtuadhsglxh@e107158-lin.cambridge.arm.com> <20190904130628.GE144846@google.com> <20190904154000.GJ240514@google.com> <20190904174707.GV2332@hirez.programming.kicks-ass.net> In-Reply-To: <20190904174707.GV2332@hirez.programming.kicks-ass.net> From: Alexei Starovoitov Date: Wed, 4 Sep 2019 10:53:38 -0700 Message-ID: Subject: Re: [PATCH 2/2] sched/debug: add sched_update_nr_running tracepoint To: Peter Zijlstra Cc: Joel Fernandes , Qais Yousef , Valentin Schneider , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , LKML , Ingo Molnar , Thomas Gleixner , Borislav Petkov , Dave Hansen , Steven Rostedt , "H. Peter Anvin" , Andy Lutomirski , =?UTF-8?Q?Jirka_Hladk=C3=BD?= , =?UTF-8?B?SmnFmcOtIFZvesOhcg==?= , X86 ML 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 Wed, Sep 4, 2019 at 10:47 AM Peter Zijlstra wrote: > > On Wed, Sep 04, 2019 at 08:51:21AM -0700, Alexei Starovoitov wrote: > > Anything in tracing can be deleted. > > Tracing is about debugging and introspection. > > When underlying kernel code changes the introspection points change as well. > > Right; except when it breaks widely used tools; like say powertop. Been > there, done that. powertop was a lesson learned, but it's not a relevant example anymore. There are more widely used tools today. Like bcc tools. And bpftrace is quickly gaining momentum and large user base. bcc tools did break already several times and people fixed them.