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=-11.6 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 B1EF8C433E2 for ; Mon, 14 Sep 2020 19:45:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6A6C320756 for ; Mon, 14 Sep 2020 19:45:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="KG+BHMRL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726028AbgINTpk (ORCPT ); Mon, 14 Sep 2020 15:45:40 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:51270 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725951AbgINTpi (ORCPT ); Mon, 14 Sep 2020 15:45:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600112736; 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=O9EeupZxGqiAaLUu6ylggzlQguNqzCnvHeCIMXXYQfs=; b=KG+BHMRLsslVt97q7h1u+lDRhGqpIzUwM5D4pwC+KrfV8xyBU7k+2BOAO2frt7mI2TXo1X pTTPqaT49UxysvGoRvrw4HOvTg/MCpIiUtCfp8uj6mRHUkTZAZ+oR1eyEu7NmeBaM4+o72 YnZSF1ox0Tt/J0UBpqNaKrev8fnZQM4= 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-533-9_JdyIa5MXSsB-6aa9uUBw-1; Mon, 14 Sep 2020 15:45:34 -0400 X-MC-Unique: 9_JdyIa5MXSsB-6aa9uUBw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 65A141074642; Mon, 14 Sep 2020 19:45:32 +0000 (UTC) Received: from krava (unknown [10.40.192.180]) by smtp.corp.redhat.com (Postfix) with SMTP id F120D10013BD; Mon, 14 Sep 2020 19:45:28 +0000 (UTC) Date: Mon, 14 Sep 2020 21:45:27 +0200 From: Jiri Olsa To: Stephane Eranian Cc: Jiri Olsa , Arnaldo Carvalho de Melo , lkml , Peter Zijlstra , Ingo Molnar , Mark Rutland , Namhyung Kim , Alexander Shishkin , Michael Petlan , Song Liu , "Frank Ch. Eigler" , Ian Rogers , Alexey Budankov , Andi Kleen , Adrian Hunter Subject: Re: [PATCH 02/26] perf: Introduce mmap3 version of mmap event Message-ID: <20200914194527.GP1714160@krava> References: <20200913210313.1985612-1-jolsa@kernel.org> <20200913210313.1985612-3-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 13, 2020 at 11:41:00PM -0700, Stephane Eranian wrote: > On Sun, Sep 13, 2020 at 2:03 PM Jiri Olsa wrote: > > > > Add new version of mmap event. The MMAP3 record is an > > augmented version of MMAP2, it adds build id value to > > identify the exact binary object behind memory map: > > > > struct { > > struct perf_event_header header; > > > > u32 pid, tid; > > u64 addr; > > u64 len; > > u64 pgoff; > > u32 maj; > > u32 min; > > u64 ino; > > u64 ino_generation; > > u32 prot, flags; > > u32 reserved; > > u8 buildid[20]; > > char filename[]; > > struct sample_id sample_id; > > }; > > > > Adding 4 bytes reserved field to align buildid data to 8 bytes, > > so sample_id data is properly aligned. > > > > The mmap3 event is enabled by new mmap3 bit in perf_event_attr > > struct. When set for an event, it enables the build id retrieval > > and will use mmap3 format for the event. > > > > Keeping track of mmap3 events and calling build_id_parse > > in perf_event_mmap_event only if we have any defined. > > > > Having build id attached directly to the mmap event will help > > tool like perf to skip final search through perf data for > > binaries that are needed in the report time. Also it prevents > > possible race when the binary could be removed or replaced > > during profiling. > > > > Signed-off-by: Jiri Olsa > > --- > > include/uapi/linux/perf_event.h | 27 ++++++++++++++++++++++- > > kernel/events/core.c | 38 +++++++++++++++++++++++++++------ > > 2 files changed, 57 insertions(+), 8 deletions(-) > > > > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > > index 077e7ee69e3d..facfc3c673ed 100644 > > --- a/include/uapi/linux/perf_event.h > > +++ b/include/uapi/linux/perf_event.h > > @@ -384,7 +384,8 @@ struct perf_event_attr { > > aux_output : 1, /* generate AUX records instead of events */ > > cgroup : 1, /* include cgroup events */ > > text_poke : 1, /* include text poke events */ > > - __reserved_1 : 30; > > + mmap3 : 1, /* include bpf events */ > > + __reserved_1 : 29; > > > what happens if I set mmap3 and mmap2? hum bad things probably ;-) I think mmap3 would overload mmap2 > > I think using mmap3 for every mmap may be overkill as you add useless > 20 bytes to an mmap record. > I am not sure if your code handles the case where mmap3 is not needed > because there is no buildid, e.g, anonymous memory. > It seems to me you've written the patch in such a way that if the user > tool supports mmap3, then it supersedes mmap2, and thus > you need all the fields of mmap2. But if could be more interesting to > return either MMAP2 or MMAP3 depending on tool support > and type of mmap, that would certainly save 20 bytes on any anon mmap. > But maybe that logic is already in your patch and I missed it. I like peter's idea of ditching mmap3 and use that maj/min.. area in mmap2 for buildid based on misc bits jirka