Application performance with "-mt" option

Question

I am seeing an improved performance when my application is compiled with "-mt". But there is something strange that my program don't use thread features. The same program compiled without "-mt" slower 10%. My program generate 10 million integers and sort the values using quick sort algorithm. (The sorting algorithm borrowed from free BSD's qsort.c)
compiler: Workshop Compiler 4.2
OS: SunOS 5.6
system: sun4u sparc SUNW,Ultra-1
$ CC -O a.C # normal compilation
$ /bin/time a.out
real: 1:18.3
user: 1:16.3
sys : 0.5
$ CC -O -mt a.C # compile with "-mt"
$ /bin/time a.out
real: 1:10.2
user: 1.08.3
sys : 0.5
a.C program don't use system call, memory allocation, I/O operation, multi-thread. It simply compare & move integers and use recursion.
What happen if I use "-mt" option with non-threaded application ?

Answer 1

The call itself is pretty cheap. If you are calling it from a middle tier, though, it may increase the "chatter" generated by the application. If you're generating an extra packet every second to make these calls, there could be an issue.
Justin
Distributed Database Consulting, Inc.
http://www.ddbcinc.com/askDDBC