Re: [boost] [xpressive] Performance Tuning?

Subject: Re: [boost] [xpressive] Performance Tuning?
From: David Abrahams (dave_at_[hidden])
Date: 2009-07-28 15:49:42

on Tue Jul 28 2009, Edward Grace <ej.grace-AT-imperial.ac.uk> wrote:

> This?
>
> http://tinyurl.com/kk858o
>
> There's some interesting trickery in there by the looks of things for eliminating the
> optimiser nastiness - that's not something I've  thought about much I'll take a look.
>
> In the comments,
>
> 42 	// operation to at least update the L1 cache.  *** Note: This
> 43 	// concern is specific to the particular application at which
> 44 	// we're targeting the test. ***
>
> that seems quite important but a little opaque out of context.

It means the application we were going to use this technique on was
going to update a long series of accumulators, which will certainly not
fit in a few registers.  We wanted to force the test to reflect that
reality.

> One thing I take exception to is the (effective) use of the mean as a
> measurement of central tendency

Why?

> - perhaps their trickery has eliminated the heavy tail.

Why would one assume there is a heavy tail in the first place?

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com