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Return probes
- From: Perry Cheng <perryche at us dot ibm dot com>
- To: systemtap at sources dot redhat dot com
- Date: Sat, 3 Mar 2007 21:59:36 -0500
- Subject: Return probes
The systemtap script below fails but works if the return probe is omitted.
In general, I have not been able to get return probes to work regardless
of what the return probe body is and ultimately I boiled it down to the
following. Once this scripts starts running, I can get it to crash by
starting some processes (fork causes page fault for copy-on-write) by
logging into the machine a few times. I am using a very recent version
of stap (version 0.5.13 built 2007-02-12) running on a 2.6.16 kernel
modified with real-time enhancements (specifically 2.6.16-rtj12.11smp). Is
there a known problem with return probes and are there workarounds?
probe kernel.function("__handle_mm_fault")
{
doZero()
}
probe kernel.function("__handle_mm_fault").return
{
doZero()
}
function doZero()
{
}
Perry