strace your web server process

strace your web server process
% /usr/sbin/apache2 -X &
[1] 16367
(hit page a few times to warm up caches)
% strace -p 16367 -o sys1.txt
Process 16367 attached - interrupt to quit
(hit page once)
Process 16367 detached
% grep stat sys1.txt | grep -v fstat | wc -l
153