------- Comment #3 from changpeng dot fang at amd dot com 2010-05-27 23:51
-------
I did a quick look at 434.zeusmp and found that prefetching for the following
simple loop is responsible:
linpck.f: 131:
c
c code for increment not equal to 1
c
ix = 1
smax = abs(sx(1))
ix = ix + incx
do 10 i = 2,n
if(abs(sx(ix)).le.smax) go to 5
isamax = i
smax = abs(sx(ix))
5 ix = ix + incx
10 continue
Prefetching for this loop seems too aggressive with unknown incx. It is not
precditable which sx(ix) will cause cache miss.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44297
