2004.09.16 19:12 "[Tiff] BigTIFF Tag Value Count issue", by Joris Van Damme

2004.09.17 02:58 "Re: [Tiff] BigTIFF Tag Value Count issue", by Bob Friesenhahn

I have attached source for a small test program I used to see how systems behave under load when using memory mapped files. Naturally, documentation is poor and the code is meant for hacking. :-)

Here are some results just obtained from running the mmap file update benchmark on some modern systems with fast CPUs and fast disks. Maybe someone can modify the benchmark to use stdio or read/write and see how performance compares with mmap?

Solaris 9:

% time ./mmaptest 16
File length = 6442450941
Stride = 131072
./mmaptest 16 4.92s user 50.81s system 44% cpu 2:06.55 total

Linux 2.6.7:

% time ./mmaptest 16
File length = 6442450941
Stride = 65536
./mmaptest 16 2.54s user 13.28s system 11% cpu 2:17.95 total

FreeBSD 5.0:

% time ./mmaptest 16
File length = 6442450941
Stride = 65536
./mmaptest 16 4.12s user 76.41s system 35% cpu 3:46.18 total

======================================
Bob Friesenhahn
bfriesen@simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen