Re: Discard support (was Re: [PATCH] swap: send callback when swap slot is freed)

Matthew Wilcox
2009-08-14T23:45:41Z

On Fri, Aug 14, 2009 at 05:21:32PM -0600, Chris Worley wrote:
> Sooner is better than waiting to coalesce. The longer an LBA is
> inactive, the better for any management scheme. If you wait until
> it's reused, you might as well forgo the advantages of TRIM/UNMAP. If
> a the controller wants to coalesce, let it coalesce.

I'm sorry, you're wrong. There is a tradeoff point, and it's different
for each drive model. Sending down a steady stream of tiny TRIMs is
going to give terrible performance.

--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."