From owner-freebsd-hackers@FreeBSD.ORG Sun Feb 15 14:33:45 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C29A81065670 for ; Sun, 15 Feb 2009 14:33:45 +0000 (UTC) (envelope-from jkoshy.freebsd@gmail.com) Received: from ti-out-0910.google.com (ti-out-0910.google.com [209.85.142.188]) by mx1.freebsd.org (Postfix) with ESMTP id 5429D8FC1D for ; Sun, 15 Feb 2009 14:33:44 +0000 (UTC) (envelope-from jkoshy.freebsd@gmail.com) Received: by ti-out-0910.google.com with SMTP id a1so1194171tib.3 for ; Sun, 15 Feb 2009 06:33:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:to:cc :subject:in-reply-to:references:user-agent:mime-version:content-type :from:date; bh=O645SiU7c4kSo/YcTEXNX0iM7YvW0F3OZ8RVSInOjO0=; b=ev5nHu6Go4BfEZmuUU3dudk23T+qKU/2fB3C/ForDN6sgOzwQDu+wUhyADU40qIFBt VtKmK21F69SUmB+3BFlVa52ngcyuAzPUH/c21/bpGNuh+OVqO2SPtTSMneigptiSl38f LwgAG9hNnpASQr857dIwxew13ilyBAOxbN/oo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:to:cc:subject:in-reply-to:references:user-agent :mime-version:content-type:from:date; b=om8D2ZhmE+gLDviviE3bp4T/yDown+QVyaEwRrV2xHdgrPKPN7v5np6Q8Va2w68f2R SBGUd51c0mccFhwKRvm5WX8em/r+N2gzqx1DMkXgrmHLL5faHJ6ahVOp0uF3R3ZYxe5e puBlHc4iW2KsyXZ5gpGv0p8j8yI9bkvqOQZJc= Received: by 10.110.86.3 with SMTP id j3mr6940952tib.51.1234706651491; Sun, 15 Feb 2009 06:04:11 -0800 (PST) Received: from moria.unixconsulting.co.in ([117.195.163.228]) by mx.google.com with ESMTPS id b7sm8638038tic.15.2009.02.15.06.04.05 (version=TLSv1/SSLv3 cipher=RC4-MD5); Sun, 15 Feb 2009 06:04:09 -0800 (PST) Sender: Joseph Koshy Message-ID: <86skmfztrm.wl%koshy@unixconsulting.co.in> To: Robert Watson In-Reply-To: References: <200902121717.47841.max@love2party.net> <4994516B.8060703@freebsd.org> <200902121754.24536.max@love2party.net> User-Agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (=?ISO-8859-4?Q?Shij=F2?=) APEL/10.7 Emacs/22.3 (amd64-portbld-freebsd6.3) MULE/5.0 (SAKAKI) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII From: Joseph Koshy Date: Sun, 15 Feb 2009 13:59:41 -0000 Cc: Sam, Joseph Koshy , Leffler , freebsd-hackers@freebsd.org, Max Laier , Andrew Brampton Subject: Re: pahole - Finding holes in kernel structs X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 15 Feb 2009 14:33:46 -0000 > Well, I think we want to inform this through actual measurement. Right now, > tools like hwpmc track cache misses by point in executable code, but what > would be nice is if we could post-process to generate cache miss information > by data structure field... That is one of the tools that I've had in mind. The hard part in the process is tracking sample locations back to source artifacts with acceptable accuracy. I couldn't find existing libraries with a compatible open-source license that I could build on, and thus the motivation for some of the libraries listed in the roadmap at http://elftoolchain.sourceforge.net/. Also, hwpmc(4) would need to be augmented to use "precise" sampling on the hardware that supports it, but this is relatively straightforward. Koshy