[R-SIG-Mac] Performance Issues.

Ken Beath kjbeath at kagi.com
Wed May 17 12:25:59 CEST 2006

On 17/05/2006, at 8:00 PM, Simon Urbanek <simon.urbanek at r- 
project.org> wrote:
> We had a discussion about this earlier, it started with
> https://stat.ethz.ch/pipermail/r-sig-mac/2006-March/002722.html
> What it boils down to is that ptATLAS can give you a good speed-up,
> but it can also screw you up by calling malloc/free all the time - it
> depends on the task. For single core CPUs it's definitely better to
> use R's own BLAS. For Core Duos it depends on the size of the problem
> - for bigger problems ptATLAS is better, for smaller problems
> internal BLAS may be better.
> In a quiet minute I'll try to run our benchmarks with Lea's allocator
> and see if it would make sense to use it for OS X.

A posting from the Scitech mailing list may be of interest.

Date: Thu, 4 May 2006 13:14:35 -0700
From: Ian Ollmann <iano at apple.com>
Subject: Re: No Accelerate.framework threading on Intel
To: scitech at lists.apple.com
Message-ID: <EBED1267-00B7-4A04-9A0C-E621621E46B8 at apple.com>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

Accelerate's BLAS is currently not threaded on Intel.  The version
that is currently out was tuned for the developer preview machines
-- Pentium 4, uniprocessor. On those machines, threading just got   
mapped to hyperthreading which didn't do much but slow it down.

The other parts of Accelerate.framework should generally be in much
better shape. We're working hard to patch up the remaining holes.

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