Xen devel - Jun 2006 - [PATCH][Resend] Output Virtual Block Device requests information ver. 3

Hi.

These patches provide the function to output the information to sysfs.
I changed the location to outputs statistical information of virtual block
device (VBD) from the /proc file system to the sysfs.
The location is ''statstics'' directory under each VBD
directory, for example, /sys/devices/xen-backend/vbd-x-xxxx/statistics.

The ''statistics'' directory includes the following three
statistical informations.
  oo_req
       is the number of Out of(?) requests.
  rd_req
       is the number of pended READ requests.
  wr_req
       is the number of pended WRITE requests.

Examples are as follows.
By applying this patch, sysfs creates "statistics" directory under the
"vbd-*" directory.
The "statistics" directory includes three statistical information
files  of VBD;  oo_req, rd_req, wr_req.

  [root@Domain-0 ~]# ls /sys/devices/xen-backend/vbd-1-2049/
  bus      driver  nodename         power       uevent
  devtype  mode    physical_device  statistics
  [root@Domain-0 ~]# ls /sys/devices/xen-backend/vbd-1-2049/statistics/
  oo_req  rd_req  wr_req
  [root@Domain-0 ~]# cat /sys/devices/xen-backend/vbd-1-2049/statistics/oo_req
  0
  [root@Domain-0 ~]# cat /sys/devices/xen-backend/vbd-1-2049/statistics/rd_req
  1592
  [root@Domain-0 ~]# cat /sys/devices/xen-backend/vbd-1-2049/statistics/wr_req
  565
  [root@Domain-0 ~]#



Changing from ver. 2 is a following.
 - Code is clearly by moving xenbus.c
 - Do not change the type of each information.
       (It may be more desirable to change into unsigned into or unsigned long)
       (But it is not essence for this mechanism)
 - Macro changes not using fmt representation (use like printf)
 

Thanks,
Satoshi UCHIDA


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