Re: [Lsf] IO less throttling and cgroup aware writeback (Was: Re: Preliminary Agenda and Activities for LSF)

Dave Chinner
2011-04-01T07:23:51Z

On Fri, Apr 01, 2011 at 02:32:54AM -0400, Christoph Hellwig wrote:
> On Fri, Apr 01, 2011 at 03:36:05PM +1100, Dave Chinner wrote:
> > > If that's a concern,
> > > can filesystem mark that bio (REQ_META?) and throttling logic can possibly
> > > let these bio pass through.
> >
> > We already tag most metadata IO in this way.
>
> Actually we don't tag any I/O that way right now. That's mostly
> because REQ_META assumes it's synchronous I/O and cfg and the block
> layer give id additional priority, while in XFS metadata writes
> are mostly asynchronous. We'll need a properly defined REQ_META
> to use it, which currently is not the case.

Oh, I misread the code in _xfs_buf_read that fiddles with
_XBF_RUN_QUEUES. That flag is dead then, as is the XBF_LOG_BUFFER
code which appears to have been superceded by the new XBF_ORDERED
code. Definitely needs cleaning up.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com