From owner-freebsd-hackers@FreeBSD.ORG  Tue Apr  9 18:47:30 2013
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id EB1C2F56
 for <freebsd-hackers@freebsd.org>; Tue,  9 Apr 2013 18:47:30 +0000 (UTC)
 (envelope-from etnapierala@gmail.com)
Received: from mail-ee0-f46.google.com (mail-ee0-f46.google.com [74.125.83.46])
 by mx1.freebsd.org (Postfix) with ESMTP id 7CCF922B
 for <freebsd-hackers@freebsd.org>; Tue,  9 Apr 2013 18:47:30 +0000 (UTC)
Received: by mail-ee0-f46.google.com with SMTP id d49so2071762eek.5
 for <freebsd-hackers@freebsd.org>; Tue, 09 Apr 2013 11:47:29 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
 h=x-received:sender:subject:mime-version:content-type:from
 :in-reply-to:date:cc:content-transfer-encoding:message-id:references
 :to:x-mailer; bh=x1nAEwftGcUxzQZNYzVwjYh1kxm82G5lF1n7/jHp1Pc=;
 b=hPsx5We8AXRN59G0/+DS/3k1RXWqMjpkxOnkIaRxENUNKAW7Chvd5TNBdPvuMSlZb/
 DOKD5J9788yhOUXLwcfZdOL7ZO3HWeamA7BVDPdDsT/kci0+U3r+CTXcaXQcDKsQjV/v
 B2QRRc/FMzN32Db7LNPYK0uhjuby6lvc5NHdUx3YH+zu2iBWfXmn/s+1Bl7yMJldEGXH
 EK9yRFwe179kCJW9hJZ06HYbg520/Ygk2n+5QhnYK4h76qxqHhEf0ZfLC/zxSE8kVwiq
 TrqlVSOgh4mCi2AO1EFcNpLOdxK0x8hXCoHG22T8OhMVTVf/TmVeF2DtW0sWEGL6zYWx
 4J6w==
X-Received: by 10.14.107.69 with SMTP id n45mr40864720eeg.23.1365533249456;
 Tue, 09 Apr 2013 11:47:29 -0700 (PDT)
Received: from [192.168.1.104] (45.81.datacomsa.pl. [195.34.81.45])
 by mx.google.com with ESMTPS id a41sm5358699eei.4.2013.04.09.11.47.27
 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128);
 Tue, 09 Apr 2013 11:47:28 -0700 (PDT)
Sender: =?UTF-8?Q?Edward_Tomasz_Napiera=C5=82a?= <etnapierala@gmail.com>
Subject: Re: GSOC 2013 project " Kernel Size Reduction for Embedded System "
Mime-Version: 1.0 (Apple Message framework v1283)
Content-Type: text/plain; charset=us-ascii
From: =?iso-8859-2?Q?Edward_Tomasz_Napiera=B3a?= <trasz@FreeBSD.org>
In-Reply-To: <CAOjFWZ6ytuKFHYBvrNTMwK8f=_ZDnGY5-naVqscC6YWZ33P8UA@mail.gmail.com>
Date: Tue, 9 Apr 2013 20:47:26 +0200
Content-Transfer-Encoding: 7bit
Message-Id: <92799D4C-797C-4304-B299-DD1DBA49CFFC@FreeBSD.org>
References: <CAOhv3dpTM9J9oiLpdw8xOAToXT_tQ3VW4Mv1F+8n7xhG+JK93w@mail.gmail.com>
 <alpine.BSF.2.00.1304091935490.13342@wojtek.tensor.gdynia.pl>
 <516452C7.7040607@mu.org>
 <alpine.BSF.2.00.1304091953060.13438@wojtek.tensor.gdynia.pl>
 <CAOjFWZ6ytuKFHYBvrNTMwK8f=_ZDnGY5-naVqscC6YWZ33P8UA@mail.gmail.com>
To: Freddie Cash <fjwcash@gmail.com>
X-Mailer: Apple Mail (2.1283)
Cc: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>,
 Alfred Perlstein <bright@mu.org>, Amit Rawat <aamitr4@gmail.com>,
 FreeBSD Hackers <freebsd-hackers@freebsd.org>
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
 <freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-hackers>, 
 <mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
 <mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 09 Apr 2013 18:47:31 -0000

In order to optimize - in this case for size - we need a way to measure
what should we focus on, and it looks like we don't have it yet.

Would it be possible to write a tool - e.g. by instrumenting LLVM - that
would make it possible to calculate, for every function in the call graph,
the amount of code in that function and everything it "pulls in", i.e. all
the code paths that it might call.  When we have that, clustering the graph
should give us some idea what to focus on.

Or perhaps such a tool already exists?

-- 
If you cut off my head, what would I say?  Me and my head, or me and my body?