Script to look for system call errors

[William Cohen]

Eugene Teo wrote:
> Hi all,
> 
> Last night I was working on a script to look for system call errors.
> This is particularly useful for identifying misbehaving userspace
> applications. The script prints out useful information about the top 20
> errors every 5 secs.
> 
> With the script, I found out that mixer_applet2 wakes up very
> frequently[1], gnome-panel tries to add a collection of watches every
> second for files that do not exist, hald tries to open some
> battery-related sysfs files over and over again even though I am running
> the script in a virtual machine. mjw has a couple of interesting
> observations with the script as well.
> 
> Take a look at the example output in errsnoop.txt.
> 
> Any feedback on this script would be appreciated.
> 
> [1] http://bugzilla.gnome.org/show_bug.cgi?id=370937
> 
> Thanks, Eugene
> 

Hi Eugene,

Looks like a cool script. It would be great to include this in the systemtap
examples.

Why bother to have:

	if ([t, p] in trace) {
		argstr = trace[t, p]
		delete trace[t, p]
	}

Why not j

ust have:
	argstr = trace[t, p]
	delete trace[t, p]

argstr needs to be set anyway.

-Will