Thank you for reply！
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 .jpeg
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
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?
Edsel
2015-10-22 9:22 GMT+08:00 Fam Zheng :
> 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/write a
> .txt
> > file. Our final goal is to generate a report for target process/file '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 (probably
> QEMU
> > 0.9), and the implementation point they had is dma_buf_rw(). The
> > information in their report shows pid, timestamps, disk sector, buffer
> size
> > and write/read for a target file (I am not even sure if such information
> 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 certain
> > 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 (not
> sure
> > if relative)
> >
>
