Re: [PATCH 1/3] xfs: introduce an allocation workqueue

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Tue, Jul 19, 2011 at 11:24:50AM +1000, Dave Chinner wrote:
> Honestly, I'd prefer not to do that because it's a slippery slope.
> I've got plenty more "do stuff in the background via workqueues"
> patches lined up, so if we start adding knobs/mount options to turn
> each of them off "just in case there's an issue".
> 
> So far I haven't found any issues at all and I've been running this
> split allocation stack like this in -all- my performance testing for
> the past 2-3 months. I know that is not conclusive, but if the
> bechmarks I've been using to improve XFS performance over the past
> 18 months don't show regressions, that's fairly indicative of the
> fact that most workloads won't even notice the change....

Maybe.  One thing I'd like to see is stuff like high-iop direct or
O_SYNC I/O that actually calls the allocator.