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

Vivek Goyal
2011-04-21T15:08:05Z

On Fri, Apr 01, 2011 at 08:56:54AM -0400, Christoph Hellwig wrote:
> On Fri, Apr 01, 2011 at 06:23:48PM +1100, Dave Chinner wrote:
> > 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 code which appears to have been superceded by the new XBF_ORDERED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.
>
> Yes, that's been on my todo list for a while, but I first want a sane
> defintion of REQ_META in the block layer.

Will splitting REQ_META in two will help. Say REQ_META_SYNC and
REQ_META_ASYNC. So meta requests which don't require any kind of priority
boost at CFQ can mark these REQ_META_ASYNC (XFS).

- So we retain the capability to mark metadata requests
- Priority boost only for selected meta data.
- Throttling can use this to avoid throttling meta data.

Thanks
Vivek