s390x-gf2m.pl: commentary update (final performance numbers turned to be

# The module implements bn_GF2m_mul_2x2 polynomial multiplication used

# in bn_gf2m.c. It's kind of low-hanging mechanical port from C for

# the time being... gcc 4.3 appeared to generate poor code, therefore

# the effort. The module delivers 55%-90% improvement on haviest ECDSA

# verify and ECDH benchmarks for 163- and 571-bit keys on z990, and

# 25%-30% - on z196(*). This is for 64-bit build. In 32-bit "highgprs"

# case improvement is even higher, for example on z990 it was measured

# 80%-150%. ECDSA sign is modest 9%-12% faster. Keep in mind that

# these coefficients are not ones for bn_GF2m_mul_2x2 itself, as not

# all CPU time is burnt in it...

# the effort. And indeed, the module delivers 55%-90%(*) improvement

# on haviest ECDSA verify and ECDH benchmarks for 163- and 571-bit

# key lengths on z990, 30%-55%(*) - on z10, and 70%-110%(*) - on z196.

# This is for 64-bit build. In 32-bit "highgprs" case improvement is

# even higher, for example on z990 it was measured 80%-150%. ECDSA

# sign is modest 9%-12% faster. Keep in mind that these coefficients

# are not ones for bn_GF2m_mul_2x2 itself, as not all CPU time is

# burnt in it...

#

# (*)	Though no improvement could be measured if compared to code

#	generated by gcc 4.1. Keep in mind that z196 is out-of-order

#	execution core and is better at executing poor code.

# (*)	gcc 4.1 was observed to deliver better results than gcc 4.3,

#	so that improvement coefficients can vary from one specific

#	setup to another.

$flavour = shift;