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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C949CC433E2 for ; Wed, 16 Sep 2020 20:58:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7425920731 for ; Wed, 16 Sep 2020 20:58:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600289900; bh=AnwlNmtnOynVuh2z7BTPG/HzLHmCwkA8RYapHph0iKo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=NcHuCQs5zlCBDRlR1flcxcr8ewusnABISrqMkfR6lLf8Eanr+JYuqDPV/A9rRTOiT gScgrYjLRmnt7t1Yl6XP1O3OPj1otHqr/LhaEU4o1H4cU+NtbXc6kHwjGA1UC/htRJ g3OBPCb+i4B6HBMVSpHnOgf6eY3ylayYF4zPiNeo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728600AbgIPU6T (ORCPT ); Wed, 16 Sep 2020 16:58:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:44498 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726538AbgIPQdP (ORCPT ); Wed, 16 Sep 2020 12:33:15 -0400 Received: from quaco.ghostprotocols.net (unknown [179.97.37.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 151CC22288; Wed, 16 Sep 2020 15:42:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600270962; bh=AnwlNmtnOynVuh2z7BTPG/HzLHmCwkA8RYapHph0iKo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=yYHsivDVhiM9Ai44rki7DnkAeYAvcS4RSXKbhNS2d2zNis4SBaaE/4lPMMgyxid0f adx/DMBOAqSqz3jJ3VEvDH1XlPEiLZYAiKhLCFNC+JLaHmxNDxYrjBibovURc7d0lq rgOfnBXUllBjmUUHmeYWRzQWquC549Of+auteO5A= Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 6BA1F400E9; Wed, 16 Sep 2020 12:42:39 -0300 (-03) Date: Wed, 16 Sep 2020 12:42:39 -0300 From: Arnaldo Carvalho de Melo To: Jiri Olsa Cc: peterz@infradead.org, Ian Rogers , Jiri Olsa , lkml , Ingo Molnar , Mark Rutland , Namhyung Kim , Alexander Shishkin , Michael Petlan , Song Liu , "Frank Ch. Eigler" , Stephane Eranian , Alexey Budankov , Andi Kleen , Adrian Hunter Subject: Re: [PATCH 16/26] perf tools: Synthesize modules with mmap3 Message-ID: <20200916154239.GT720847@kernel.org> References: <20200913210313.1985612-1-jolsa@kernel.org> <20200913210313.1985612-17-jolsa@kernel.org> <20200914160758.GK160517@kernel.org> <20200916082018.GA2301783@krava> <20200916140744.GR720847@kernel.org> <20200916141700.GC1362448@hirez.programming.kicks-ass.net> <20200916151021.GS720847@kernel.org> <20200916152123.GH2301783@krava> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200916152123.GH2301783@krava> X-Url: http://acmel.wordpress.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Wed, Sep 16, 2020 at 05:21:23PM +0200, Jiri Olsa escreveu: > On Wed, Sep 16, 2020 at 12:10:21PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Wed, Sep 16, 2020 at 04:17:00PM +0200, peterz@infradead.org escreveu: > > > On Wed, Sep 16, 2020 at 11:07:44AM -0300, Arnaldo Carvalho de Melo wrote: > > > > Em Wed, Sep 16, 2020 at 10:20:18AM +0200, Jiri Olsa escreveu: > > > > > > IIRC BUILD_ID_SIZE is 20 bytes which is the correct size for SHA-1. A > > > > > > build ID may be 128-bits (16 bytes) if md5 or uuid hashes are used. > > > > > > Should this test just be "> 0" ? > > > > > ah right, will check on that > > > > And how do you deal with this in the kernel? I.e. to inform userspace, > > > > via the PERF_RECORD_MMAP3 (or MMAP2 with that misc bit trick) the size > > > > of the build-id? > > > The union size is 24 bytes, so there's plenty space to store a length > > > field with the buildid. > > So, I think we should instead use a bit in the misc field, stating the > > kind of build-id, so that we don't waste a byte for that, I think. > not sure there's too many misc bits left if there would be more > build id kinds So, Ian mentioned a few types of build ids, if there are not that many misc bits left for PERF_RECORD_MMAP2, then yeah, we can then use one byte and use it as a PERF_RECORD_MMAP2 specific misc bits, me may want to have something else in the future, like we're now reusing those ino, etc, to instead store a build-id. But we're closing in to a final solution, and that is good. :-) - Arnaldo