From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58512) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zp9n2-0003FY-Ox for qemu-devel@nongnu.org; Thu, 22 Oct 2015 02:55:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zp9mx-0006QU-OZ for qemu-devel@nongnu.org; Thu, 22 Oct 2015 02:55:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52995) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zp9mx-0006QP-GR for qemu-devel@nongnu.org; Thu, 22 Oct 2015 02:55:51 -0400 Date: Thu, 22 Oct 2015 14:55:47 +0800 From: Fam Zheng Message-ID: <20151022065547.GG11063@ad.usersys.redhat.com> References: <20151022012239.GB11063@ad.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] Functions to intercept Disk IO information? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: QuQ Edsel Cc: qemu-devel@nongnu.org On Thu, 10/22 14:18, QuQ Edsel wrote: > Thank you for reply=EF=BC=81 > But as I insert a printf message in dma_buf_rw, compile and boot up the= VM, > there are no messages printed even when I open/create/edit a .txt or .j= peg > file ? > If dma_buf_rw is called it is supposed to print messages in the monitor= ... > On the other hand, > the dma_blk_io called in ide_dma_ cb did happen when files are > manipulated.... Yes, it was a mistake, I meant dma_blk_io, sorry for confusion. :) dma_bu= f_rw only works for some device types, while dma_blk_io works more commonly. > Would it be point to determine Disk IO and to intercept the information= I > need? > Sorry I really lack knowledge in this field... > Does the PIO you mentioned means NIC IO? PIO is port I/O which doesn't use DMA. Fam >=20 > Edsel >=20 > 2015-10-22 9:22 GMT+08:00 Fam Zheng : >=20 > > On Thu, 10/22 01:13, QuQ Edsel wrote: > > > Hi, > > > My friends and I were assigned a task to find out a point to insert= a > > > callback function to intercept Disk IO activities such as read/writ= e a > > .txt > > > file. Our final goal is to generate a report for target process/fil= e 's > > > Disk IO activities. We have QEMU 2.3 with KVM enabled. We have been > > looking > > > for such a point for long...but not so capable of such a task. > > > People who had this project last year done so with TEMU 1.0 (probab= ly > > QEMU > > > 0.9), and the implementation point they had is dma_buf_rw(). The > > > information in their report shows pid, timestamps, disk sector, buf= fer > > size > > > and write/read for a target file (I am not even sure if such inform= ation > > is > > > meaningful or useful) > > > Currently I have tried to printf in functions such as dma_buf_rw / > > > dma_blk_io / bdrv_aio_readv...etc. to see if they print out message= when > > I > > > open/edit/save a .txt or .jpeg file. The first one just don't print= at > > all, > > > and the second and third one print a lot after booting up the guest= .... > > > I can see that the dma_blk_io function call in ide_dma_cb (core.c) = may be > > > related because it prints as I have activities on files. However it= also > > > prints sometime when I am not doing any thing... so I not that cert= ain > > > about it. (and I don't know if write/read activities invoke such > > > function..) > > > > Yes, dma_buf_rw should handle all your I/O unless you're doing PIO. I > > think the > > other activities you see when you're not doing anything is from guest > > system's > > background tasks. > > > > Thanks, > > Fam > > > > > > > > Is there a correct /better point to intercept disk IO information > > > ?(especially for activities such as read/write a .file) > > > Or what should I do to clearly get the needed information from Disk= IO > > > functions? > > > I would be so grateful to have the information. > > > Thank you. > > > > > > The guest environment I have is 64bit Windows 7 with qcow2 image (n= ot > > sure > > > if relative) > > > > >