Re: [RFC] [Patch 0/8] statistics infrastructure

From: Frank Ch. Eigler
Date: Wed May 17 2006 - 14:55:07 EST

Hi -

On Wed, May 17, 2006 at 02:44:24PM -0400, Valdis.Kletnieks@xxxxxx wrote:
> On Wed, 17 May 2006 14:28:08 EDT, "Frank Ch. Eigler" said:
> > I am not suggesting a single solution for all needs. I wanted to
> > focus only one aspect: the marking of those points in the kernel where
> > something probeworthy occurs with hooks. [...]
> The problem is that the "common pool" ends up being a very wide swamp
> very fast. [...]
> So under your plan, all 3 groups now use a "common pool" that includes
> slap, timing, latency, and other stuff - and nobody's using more than
> 1/3 of it, but paying the performance penalty for the 2/3 unused hooks....

It may not be clear, but by "pool", I mean some group of individually
activated hooks, doing little but calling some routine of
instrumentation with a few parameters. Special-interest data like
timing, latency would be computed in the instrumentation code, not
necessarily at the hook site, so that part need incur no waste for
disinterested users.

Not-activated (dormant) hooks would indeed cost a little. The
question is how much time/space cost is acceptable, in order to reap
the benefits of widely available probing.

- FChE
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