Re: 2.6.0-test4 shocking (HT) benchmarking (wrong logic./phys. HT CPU distinction?)

[Stan Bubrouski <stan@ccs.neu.edu>]

max@vortex.physik.uni-konstanz.de wrote:
> Hello all you great Linux hackers,
> 
> in our fine physics group we recently bought a DUAL XEON P4 2666MHz, 2GB, with 
> hyper-threading support and I had the honour of making the thing work. In the 
> process I also did some benchmarking using two different kernels (stock 
> SuSE-8.2-Pro 2.4.20-64GB-SMP, and the latest and greatest vanilla 
> 2.6.0-test4). I benchmarked 
> 
> [1] kernel compiles (after 'cat'ting all files >/dev/null, into the buffer 
> cache) and 
> 
> [2] running time of a multi-threaded numerical simulation making extensive use 
> of FFTs, using the fftw.org library.
> 
> To cut the detailed story (below) short, the results puzzle me to a certain 
> extend: The physical/logical CPU distinction, which 2.6.0 is supposed to make 

I'm no kernel developer so take my opinion as worth more than
anyone else here (much less).  The new scheduler in the 2.6
kernels is still being tweaked by Con and Igno, et al.  But beyond
that there are several new ways to tweak the scheduler
designed to handled different loads, amounts of mem. etc...

Skimming the past few months of the mail list archives for
what to tweak and how may enhance the tasks you are currently
testing.  My $0.01 (I'm cheap like that).

-sb