[dm-devel] an optimization for dm-bufio and dm-integrity

[Mikulas Patocka]

On Wed, 19 Jul 2017, Milan Broz wrote:

> On 07/19/2017 05:39 PM, Mike Snitzer wrote:
> > On Wed, Jul 19 2017 at 11:30P -0400,
> > Mikulas Patocka <mpatocka at redhat.com> wrote:
> > 
> >> Hi Mike
> >>
> >> Some times ago, I sent this patch as dm-bufio optimization (it doesn't 
> >> have to write full buffers, it only writes a part of the buffer that 
> >> changed). You delayed the patch until the next kernel.
> >>
> >> Will you submit the patch to the current kernel?
> > 
> > Sorry about that.  It obviously fell off my radar.
> > 
> > I'll review it and see if I can make the justification for it going into
> > 4.13-rc2.  But unfortunately the 4.13 merge window closed this past
> > Sunday when Linus released v4.13-rc1
> > 
> > I'll let you know though, thanks.
> 
> Just FYI: I am just running some tests with the stack space fix and
> this patch and the performance improvement for 4k sectors is really big
> (compared to 4.12). It would be nice if both patches hits 4.13...
> 
> Milan

That journal allocation bugfix should definitely go to the stable 4.12 
branch.

The plug fix may or may not be backported, it provides about 60% 
performance improvement on specific write patterns (if you write this 
sequence of bytes with O_DIRECT 
4096-8191,0-4095,12288-16383,8192-12287,20480-24575,16384-20479...).

Mikulas