Subject: Re: vmstat, iostat etc no longer work?
To: Curt Sampson <firstname.lastname@example.org>
From: Jason Thorpe <email@example.com>
Date: 11/10/1996 18:47:03
On Sun, 10 Nov 1996 18:37:21 -0800 (PST)
Curt Sampson <firstname.lastname@example.org> wrote:
> To take your points in reverse order, Jason:
> > (b) We'd have to keep the kmem interface anyhow, because
> > we don't want to give up looking at kernel port-mortems.
> I don't know that this counts a a strike against /kern and /proc,
> since I would never propose giving these up, anyway. It's handy to
> be able to look at any variable in the kernel one wants to. (Although
> once a Linux fellow seemed to be claiming that you can indeed get
> the value of and change any global kernel variable through their
> /kern filesystem.)
I'm not sure of the value of this... It's nothing different than
what the kmem interface would give you...
> > (a) In order to use them, it requires people to load up
> > their kernels with kernfs and procfs. This is bad,
> > particularly in an "embedded" application. For example,
> > we have a couple of NetBSD IPv6 routers here, and the
> > kernels are lean, but being able to use iostat and
> > vmstat is good.
> Would it bloat terribly if we included the ability to do both in
> these utilities (or #ifdef'd them)? I'm sure that there are people
> out there regularly recompiling kernels that don't have the time
> and space to do the whole userland too who would be happy to have
> a userland that didn't need updates so often.
Well... let's think about this for a sec...
If you're reading actual structs and whatnot from /kern or /proc,
you have the exact same problem as if you'd used kmem, because
the format of a structure may change...
If you read strings from multiple files, then you've:
- added complexity to the program that needs the data,
- made the program that needs the data much slower than
it needs to be.
In short, you don't gain anything; in fact you lose.
Jason R. Thorpe email@example.com
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