Re: Another kvm user can go away?

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

   Date: Fri, 30 Dec 2016 16:37:14 +0800 (PHT)
   From: Paul Goyette <paul%whooppee.com@localhost>

   I have managed to provide access to all of the kernel history data via 
   sysctl, and I've come up with a modified version of vmstat(1) that can 
   read the data from sysctl rather than having to use kvm.

   Diffs for sys/sys/kernhist.h and sys/kern/kern_history.c can be found at 
   www.netbsd.org/~pgoyette/my_vmstat/kernhist.diffs  In the same directory 
   you can find a source file my_vmstat.c (and its associated Makefile).

What function does kern_history_new serve?

Why membar_producer?  No matching membar_(datadep_)consumer?

Is sysctl_createv kosher under a mutex?  I expect it may allocate
memory, so my inclination is probably not.

Can you sketch the control and data flow here?  sysctl_kernhist_helper
is the function of a new sysctl node kern.hist, but it itself
establishes new sysctl nodes, which is a curious kind of recursion.

There seem to be some stray debug prints in sysctl_kernhist_helper.