From owner-freebsd-hackers@FreeBSD.ORG Wed Sep 7 15:10:46 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 CFB7A16A41F for ; Wed, 7 Sep 2005 15:10:46 +0000 (GMT) (envelope-from nikhildharashivkar@gmail.com) Received: from rproxy.gmail.com (rproxy.gmail.com [64.233.170.200]) by mx1.FreeBSD.org (Postfix) with ESMTP id F141343D45 for ; Wed, 7 Sep 2005 15:10:45 +0000 (GMT) (envelope-from nikhildharashivkar@gmail.com) Received: by rproxy.gmail.com with SMTP id r35so1181243rna for ; Wed, 07 Sep 2005 08:10:45 -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=HVNlCRixfS1Wp7+DxmK5l/WE3v8Hob19dgAs0mX6VWIJwCuoNLji9hvzy1rwB1XQmvKXrpJroiWa0tfiF5+YJPyQFvL4fqGaZcI5VAiUMG2uq9X3qJBE1pPpeSulsFKdohTVQ8iZ7BjOlGmdw2gnfuDxFEppl26GkPf27p1cthg= Received: by 10.38.73.47 with SMTP id v47mr1128241rna; Wed, 07 Sep 2005 08:10:45 -0700 (PDT) Received: by 10.38.12.59 with HTTP; Wed, 7 Sep 2005 08:10:45 -0700 (PDT) Message-ID: <17db6d3a05090708104ff98a7c@mail.gmail.com> Date: Wed, 7 Sep 2005 20:40:45 +0530 From: Nikhil Dharashivkar To: Robert Watson In-Reply-To: <20050906125754.Y51625@fledge.watson.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> <17db6d3a0509052203b1da14a@mail.gmail.com> <20050906081855.GA26550@cirb503493.alcatel.com.au> <17db6d3a050906014048e2045b@mail.gmail.com> <20050906125754.Y51625@fledge.watson.org> Cc: Peter Jeremy , freebsd-hackers@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: Wed, 07 Sep 2005 15:10:47 -0000 Hi, I went through the ktr and ktrdump options. I compiled the kernel with options ktr. I found that ktr support is mostly for lock and schedule. We can trace drivers using mask KTR_DEV and some CTR* statements in dirver. But This ktr support is from freebsd 5. I am aslo using freebsd 4.10 and older. For this case, do I need to port KTR code for older version ? or is there any other solution ? On 9/6/05, Robert Watson wrote: > On Tue, 6 Sep 2005, Nikhil Dharashivkar wrote: >=20 > > Yes, it is ok if i loose data in ktrace queue when crash occurs. > > Basically, I want to give an Disk IO trace support to ktrace on FreeBSD= . > > So, what I am thinking to use struct dio in dastrategy routine to > > trace the IO. I 'll use this struct to generate ktr_request. Throught > > ktr_writerequest it will be written in ktrace.out . > > Is it possible ? >=20 > Try taking a look at KTR(9) and ktrdump(8) for information on ktr, the > in-kernel trace facility. ktrace(1) is almost entirely about tracing > process level system call behavior, and not structured for kernel event > tracing except in that context. I think you'll find KTR(9) is much more > what you're looking for, and among other things, you can extract the > results from both live kernels and kernel crash dumps. >=20 > Robert N M Watson >=20 >=20 > > > > > > > > On 9/6/05, Peter Jeremy wrote: > >> On Tue, 2005-Sep-06 10:33:53 +0530, Nikhil Dharashivkar wrote: > >>> Thanks for replying me. Basically what happend, while testing > >>> scsi driver on freebsd, at some point it crashes. So, there is no wa= y > >>> to know how much IO is performed. To know the IO state just before th= e > >>> driver fails, i selected ktrace to print IO information whatever i ll > >>> get from dastrategy routine. > >> > >> It's not clear how ktrace is going to help here. The ktrXXX(9) > >> functions place ktr_request events in a queue. A kernel thread then > >> dumps the queue entries into a file via the normal buffer cache. The > >> data on disk is typically about 30 seconds behind real time. If the > >> system crashes, you will lose any events that are still in the buffer > >> cache or ktr_todo queue. > >> > >> Another problem is that since ktrace generates disk I/O, it is likely > >> to disturb your testing. > >> > >> A better approach would seem to be to build a circular buffer and > >> store the I/O requests in the buffer. When the system crashes, you > >> can look at the last entries in the buffer. > >> > >> -- > >> Peter Jeremy > >> > > > > > > -- > > Thanks and Regards, > > Nikhil. > > _______________________________________________ > > freebsd-hackers@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.o= rg" > > >=20 --=20 Thanks and Regards, Nikhil.