Re: Too many PMC implementations

[Thor Lancelot Simon <tls%panix.com@localhost>]

On Thu, Aug 23, 2018 at 10:17:29AM -0700, Jason Thorpe wrote:
> 
> > On Aug 23, 2018, at 8:47 AM, Anders Magnusson <ragge%ludd.ltu.se@localhost> wrote:
> 
> > I have used it not long ago for vax.  Maybe I did have to do some tweaks, do not remember,
> > but I really want to be able to use kernel profiling on vax.
> > 
> > So, I really oppose removing it and leaving vax without any kernel profiling choice.
> 
> How hard would it be to add support for dtrace on Vax?

Without FBT, probably pretty easy.  But of course FBT is the only plausible
replacement for a statistical profiler that DTrace offers.

The basic requirement for FBT is a dynamic patcher (to really do it right);
though some __predict-false branches can be inserted at the head of every
function and a global used instead.

-- 
 Thor Lancelot Simon	                                     tls%panix.com@localhost
  "Whether or not there's hope for change is not the question.  If you
   want to be a free person, you don't stand up for human rights because
   it will work, but because it is right."	--Andrei Sakharov