Re: [patch] Performance Counters for Linux, v2

[David Miller]

From: Ingo Molnar <mingo@xxxxxxx>
Date: Mon, 8 Dec 2008 12:33:18 +0100

> Your whole statistical argument that group readout is a must-have for 
> precision is fundamentally flawed as well: counters _themselves_, as used 
> by most applications, by their nature, are a statistical sample to begin 
> with. There's way too many hardware events to track each of them 
> unintrusively - so this type of instrumentation is _all_ sampling based, 
> and fundamentally so. (with a few narrow exceptions such as single-event 
> interrupts for certain rare event types)

There are a lot of people who are going to fundamentally
disagree with this, myself included.

A lot of things are being stated about what people do with this stuff,
but I think there are people working longer in this area who quite
possibly know a lot better.  But they were blindsided by this new work
instead of being consulted, which was pretty unnice.
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