From owner-freebsd-hackers@FreeBSD.ORG Tue Sep 6 04:49:23 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8E1C816A420 for ; Tue, 6 Sep 2005 04:49:23 +0000 (GMT) (envelope-from nikhildharashivkar@gmail.com) Received: from rproxy.gmail.com (rproxy.gmail.com [64.233.170.202]) by mx1.FreeBSD.org (Postfix) with ESMTP id 102D343D46 for ; Tue, 6 Sep 2005 04:49:21 +0000 (GMT) (envelope-from nikhildharashivkar@gmail.com) Received: by rproxy.gmail.com with SMTP id r35so929921rna for ; Mon, 05 Sep 2005 21:49:21 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=LcV1R2HbewQmEt2p7nLehbUW2AzhUpEGSotNftzoFlOTuP3uNKjExtwDZxWCScVkm9jve+kYH60kkJDoCOGSGw5Xl8TrA4vCncUUk28ncgCWkn2CMnO1ca8ENDuqsYvJNPOY+WzYr1GsFACvhzEOrxhmaN4SI0CgQ8s/AX70W8g= Received: by 10.38.76.51 with SMTP id y51mr469541rna; Mon, 05 Sep 2005 21:49:21 -0700 (PDT) Received: by 10.38.12.59 with HTTP; Mon, 5 Sep 2005 21:49:21 -0700 (PDT) Message-ID: <17db6d3a05090521494a284c01@mail.gmail.com> Date: Tue, 6 Sep 2005 10:19:21 +0530 From: Nikhil Dharashivkar To: Scott Long In-Reply-To: <431C93DD.20402@samsco.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline References: <17db6d3a0509051000622868bc@mail.gmail.com> <431C8D5B.7080309@samsco.org> <431C92F2.9090104@persistent.co.in> <431C93DD.20402@samsco.org> Cc: freebsd-hackers@freebsd.org, "Rajesh S. Ghanekar" , freebsd-scsi@freebsd.org Subject: Re: Adding new option to ktrace 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: Tue, 06 Sep 2005 04:49:23 -0000 Yes, what rajesh saying is right , i want to print IO Bytes. On 9/6/05, Scott Long wrote: > Rajesh S. Ghanekar wrote: > > Scott Long wrote: > > > >> Nikhil Dharashivkar wrote: > >> > >>> Hi, > >>> i want to hack the ktrace system call. Basically, I want to monito= r > >>> scsi disk IO through dastrategy() routine. > >>> It seems that kern_ktrace.c implements different functions for > >>> ktrace options like -tc / -ti ... etc (see man page). So, is it > >>> possible to add new option for disk IO with new structure object > >>> containing disk io information which will be pass to > >>> ktr_submittrequest thr' ktr_request structure. > >>> Will data will be written correctly in ktrace.out and will > >>> kdump analyze that ? > >>> > >>> > >>> > >> > >> What are you trying to monitor? Would the existing devstat interface > >> work? > > > > > > May be he requires how many bytes transferred (read/write) while a > > process is executing. > > I guess devstat doesn't do it from process context, it gives total IO > > read/writes from a device, > > if registred via devstat. Please correct me if I am wrong. > > > > > > - Rajesh > > >=20 > There isn't a 1:1 correlation between the bytes that the userland > program writes, and the bytes that actually get written to disk. > Filesystem metadata writes will happen if the file needs to be > extended, not to mention the access time being updated. Some writes > won't even originate from a userland program, like swap writes. > GEOM also decouples the I/O path, so it's not the user process that > will actually do the write, it's the g_down kthread. I would think > that this would make tracking I/O via ktrace very hard. >=20 > Scott >=20 --=20 Thanks and Regards, Nikhil.