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 <f...@redhat.com>: > 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) > > >
