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System tap use case
- From: Phil Muldoon <pmuldoon at redhat dot com>
- To: systemtap at sourceware dot org
- Date: Tue, 21 Mar 2006 10:10:48 -0600
- Subject: System tap use case
Here's a use case that I had several years back when I worked in GES.
"We had a board we ported the Linux kernel and supporting libraries to.
The processor did not have an MMU. During the debugging phase we found
that if you subjected the board to a ping flood, it would lock up and
require a complete power off/power on. The board was embedded in nature,
and was accessed via ssh.
As the crash only happened during a ping flood - not during a normal
ping - it was very difficult to debug the network stack in the kernel,
and in the actual network driver.
The crashes happened at random intervals during the ping flood, and it
would never happen during a "normal" ping rate. ICMP with a higher
payload *seemed* to cause the crash more quickly, but that was purely
observational in nature."
How could system-tap help in this scenario?
Regards
Phil
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