Re: [Lsf] [RFC] writeback and cgroup

[Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Sat, Apr 14, 2012 at 02:25:14PM +0200, Peter Zijlstra wrote:
> On Wed, 2012-04-11 at 11:40 -0400, Vivek Goyal wrote:
> > 
> > Ok, that's good to know. How would we configure this special bdi? I am
> > assuming there is no backing device visible in /sys/block/<device>/queue/?
> > Same is true for network file systems. 
> 
> root@twins:/usr/src/linux-2.6# awk '/nfs/ {print $3}' /proc/self/mountinfo | while read bdi ; do ls -la /sys/class/bdi/${bdi}/ ; done
> ls: cannot access /sys/class/bdi/0:20/: No such file or directory
> total 0
> drwxr-xr-x  3 root root    0 2012-03-27 23:18 .
> drwxr-xr-x 35 root root    0 2012-03-27 23:02 ..
> -rw-r--r--  1 root root 4096 2012-04-14 14:22 max_ratio
> -rw-r--r--  1 root root 4096 2012-04-14 14:22 min_ratio
> drwxr-xr-x  2 root root    0 2012-04-14 14:22 power
> -rw-r--r--  1 root root 4096 2012-04-14 14:22 read_ahead_kb
> lrwxrwxrwx  1 root root    0 2012-03-27 23:18 subsystem -> ../../../../class/bdi
> -rw-r--r--  1 root root 4096 2012-03-27 23:18 uevent

Ok, got it. So /proc/self/mountinfo has the information about st_dev and
one can use that to reach to associated bdi. Thanks Peter.

Vivek