For Programmers: Free Programming Magazines  


Home > Archive > Unix Programming > December 2004 > Interesting performance difference









You are viewing an archived Text-only version of the thread. To view this thread in it's original format and/or if you want to reply to this thread please [click here]

 

Author Interesting performance difference
Gary

2004-12-22, 9:00 am

I've been testing a C routine I've written that uses zlib. The module is
compiled with xlc with -O5.

The thing I can't explain is this. Testing the module on two p615 boxes, one
is a 7029-6E3, single CPU 1.2GHz running AIX 5.1 and the other is a 7029-6C3
single CPU 1.2GHz running AIX 5.2, both machines have 1GB RAM (the test
program is small) and 2 x mirrored 36GB disks (no IO involved). The program
runs the same 8K of random data through zlib compression, followed by a base
64 encode, and it does this 50,000 times.

On the AIX 5.1 machine, the runs average real 0m22.75s, user 0m22.48s

And on the 5.2 machine, real 0m34.68s, user 0m34.33s

I'm at a loss to explain why this statically linked binary runs so much
slower on 5.2 than 5.1, given the two p615s are identically configured (save
for one being the rack version and one is the tower).

Any ideas on what could be happening or how I could identify where the extra
time is going?


Sponsored Links







Also available: Server administration forum archive | Web Design forum archive | Software forum archive | Hardware reviews archive

Copyright 2008 codecomments.com