The ABINIT Users Mailing List ( CLOSED )

[Masayoshi Mikami <mmikami@rc.m-kagaku.co.jp>]

Dear all,

Sorry for the series of the posts...
And very sorry to those who take his/her time
to dwell on this topic; In particular, Marc, I will be pleased
to owe you a bottle of special Japanese "sake" ... (next time !)

The solution : FCFLAGS_OPT="-O3 -tpp2",
whiche enables 10-15 times faster than "-O2"(default)
on Itanium2/ifort. (This is amazing !)

The previous results (the default configuration)
v.5.2.3:- Total wall clock time (s,m,h):   5824.1      97.07    1.618  
(-O3 -tpp1)
v.5.2.4:- Total wall clock time (s,m,h):  12559.0   209.32   3.489 (-O2)
v.5.3.0:- Total wall clock time (s,m,h)   13056.1    217.60  3.627 (-O2)
v.5.3.2:- Total wall clock time (s,m,h)   74086.2  1234.77  20.580 (-O2)
v.5.3.3:- Total wall clock time (s,m,h):  74144.5  1235.74  20.596 (-O2)
v.5.3.4:- Total wall clock time (s,m,h):  74040.8  1234.01  20.567 (-O2)

Then, the same test with "-O3 -tpp2"
v.5.2.3:- Total wall clock time (s,m,h):  7652.5   127.54   2.126
v.5.2.4:- Total wall clock time (s,m,h):  7529.7   125.50   2.092
v.5.3.0:- Total wall clock time (s,m,h):  7634.1   127.23   2.121
v.5.3.2:- Total wall clock time (s,m,h):  7662.8   127.71   2.129
v.5.3.3:- Total wall clock time (s,m,h):  7687.2   128.12   2.135
v.5.3.4:- Total wall clock time (s,m,h):  7723.7   128.73   2.145

So, the gap between v.5.2.3 and v.5.2.4 (about twice times),
and the other gap between v.5.3.0 and v.5.3.2 (about 6-7 times)
can be overcome just with "-O3 -tpp2".

My preoccupation came from the experience with v.4.6.x,
where I used attached makefile_macros with "-O2" ...
Oh, yikes !!  Pardon !
(Still, don't you think this optimization effect is awesome ?
 So, the binary users might want to compile the source tar.gz
 with such higher optimization ...)

Thus, I would like to suggest "-O3 -tpp2" as default in configuration
for Itanium2/ifort... Yann, how do you think ?

BTW, speaking of configuration,
knowing about "FCFLAGS_FREEFORM"/"FCFLAGS_FIXEDFORM"
might help for some old computers with old compilers that do not
understand free/fixed format automatically.

Bien a vous,
Masayoshi