Re: lz4 status?

[Chris Mason <chris.mason@fusionio.com>]

Quoting David Sterba (2013-07-10 18:54:54)
> On Sun, Jun 30, 2013 at 12:35:09PM -0500, Mitch Harder wrote:
> > There's been a parallel effort to incorporate a general set of lz4
> > patches in the kernel.
> > 
> > I see these patches are currently queued up in the linux-next tree, so
> > we may see them in the 3.11 kernel.
> 
> The patches are now merged into 3.11.
> 
> > It looks like lz4 and lz4hc will be provided.
> 
> Regarding HC mode, there are some core compression code changes needed
> in order to fully utilize the its potential, namely larger chunk size
> that's compressed at a time. There was some tiny yet measurable gain of
> HC against ordinary mode compared on current 4k-at-a-time
> implementation, but the space savings did not justify the speed drop of
> HC mode.
> 
> I can't say if the patchset will be ready for 3.12 though.

The current limits on the amount of data compressed at a time and the
amount of delayed allocation sent down at a time were pulled out of the
air.  

Changes to those limits are definitely ok if they are helping specific
workloads.

-chris