Hi Mauro, On Fri, Feb 25, 2011 at 7:03 PM, Mauro Romano Trajber <[email protected]> wrote: > I was doing some performance tests of system calls and I find an interesting > behavior. > Using RDTSC to count the CPU cycles, a single call to the getpid() consumes > about 7k of CPU clock cycles and ten calls consume approximately 9,800 > cycles. > The fact is that from the second call, the CPU cycles grows at a rate of > about 350 CPU cycles per call. > Why does this happen? There is some hardware optimization when the syscall > ID is already in EAX register ?
Use strace and check to number of getpid() syscalls. You'll notice that only 1 system call is made, glibc caching the pid value. thanks, Daniel. _______________________________________________ Kernelnewbies mailing list [email protected] http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
