[dm-devel] [PATCH 2/4] dm stats: support precise timestamps

[Vivek Goyal]

On Wed, Jun 17, 2015 at 09:17:40AM -0400, Mikulas Patocka wrote:

[..]
> > > > >  	<program_id>
> > > > >  	  An optional parameter.  A name that uniquely identifies
> > > > >  	  the userspace owner of the range.  This groups ranges together
> > > > 
> > > > We are adding these new parameters/arguments in between existing parameters.
> > > > Will it break any of the existing scritps. Will it make sense to add these
> > > > new parameters at the end. It is more intuitive.
> > > 
> > > It could break someone who uses number as program_id - but there is no 
> > > program on Linux with name that is a pure number.
> > > 
> > 
> > There does not seem to be any restriction that program_id has to be
> > a valid program name. It could be any string. I used a program id
> > of 25 and it works.
> 
> The purpose of program_id is that different programs don't step over each 
> other's statistics. Your program should use the program name as program_id 
> to make sure that it doesn't collide.

I think it would be reasonable use "pid" as program_id when different
instance of same program want to keep track of different regions of
disk.

Thanks
Vivek