[dm-devel] dm-statistics: report precise timestamps and histogram

[Mikulas Patocka]

On Tue, 18 Aug 2015, Mike Snitzer wrote:

> On Tue, Aug 18 2015 at  4:26pm -0400,
> Mikulas Patocka <mpatocka at redhat.com> wrote:
> 
> > Mike, please submit this patch to the upstream kernel before 4.2 is 
> > released, so that the all the kernels that support the options 
> > "precise_timestamps" and "histogram" also report these values back.
> 
> It is really late to be sending pull requests for 4.2 (next release is
> likely 4.2 final).  I've already sent 6 'fixes' pull requests to Linus
> for 4.2.  This patch is just too late, sorry.
> 
> But what I will do is tag this commit for 4.2-stable inclusion.
> 
> Userspace will have to check the DM ioctl version to know if DM provides
> these extra keywords.
> 
> Mike

But if you don't send it, userspace will forever have to deal with kernels 
that don't report this feature back.

You can think that not reporting these features was a bug in the original 
design and this patch fixes the bug.

Mikulas