Today, my boss want me to find some data to compare with Solaris and Linux. And I find a freeware(GPL) on Linux, called systemtap . It looks like the "DTrace" in Solaris. As the documents writes, the we have to download the kernel package then we can start to use it. The commands as the following: # yum install systemtap kernel-devel yum-utils # debuginfo-install kernel The sample "script" as the following: # stap -ve 'probe begin { log("hello world") exit () }' # stap -c df -e 'probe syscall.* \ { if (target()==pid()) log(name." ".argstr) }' Any Linux user use this before? Wish this helps. regards, Stanley Huang