------- Additional Comments From sgk at troutmask dot apl dot washington dot edu 2005-05-31 16:48 ------- Subject: Re: Really, really, horrible IO performance
On Tue, May 31, 2005 at 07:38:41AM -0000, fxcoudert at gcc dot gnu dot org wrote: > First thing: I can reproduce the timings differences on my i386-linux, > with ext3 filesystem. > > Second thing: Steve, your patch truncates files, which is not correct! > Given the following modified testcase Yes, I know. See http://gcc.gnu.org/ml/fortran/2005-05/msg00420.html. Note, I played with various combination of mmap flags with no notice difference in performance. Also, I run FreeBSD with debugging kernel features, which causes a significant increase over non-debugging kernels. I've observed that if the file does not exist, the execution time is on order of 0.01 s. With a debugging kernel, I see execution times on the order of 70 s. With a non-debugging kernel, I see times on the order of 1 s. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21820
