Re: Query about DIO/AIO WRITE throttling and ext4 serialization

[Dave Chinner <david@fromorbit.com>]

On Thu, Jun 02, 2011 at 10:17:16AM -0400, Vivek Goyal wrote:
> On Thu, Jun 02, 2011 at 11:22:09AM +1000, Dave Chinner wrote:
> > On Wed, Jun 01, 2011 at 05:50:49PM -0400, Vivek Goyal wrote:
> > > Hi,
> > > 
> > > If I throttle a DIO/AIO WRITE bio at block device in a cgroup, will it
> > > lead to any kind of serialization of ext4 file system. IOW, is there any
> > > filesystem operation which will wait for that DIO/AIO WRITE to finish
> > > before other filesystem can make progress (fsync, journalling etc?)
> > 
> > Truncate?
> > 
> > (XFS explicitly serialises truncate against in flight DIO,
> > regardless of whether ext4 does.)
> > 
> 
> Dave,
> 
> Does this serialization happens against that particular inode on which
> truncate has been called? If yes, then I think I will still be fine
> as in common use case I am not expecting much sharing of inodes across
> cgroups.

Same inode serialisation only.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com