New example script: nfstop

[David Smith]

Back at FUDCon, during the systemtap info session I helped an attendee
with a script.  He had been using a dtrace script, called nfstop, from
the following link:

<http://blogs.oracle.com/erickustarz/entry/dscript_to_retrieve_active_nfs>

I made a quick approximation of the script at the conference, but hadn't
had time to get back to it and spiffy it up a bit.

I took some time yesterday and finally made some changes.  The script
acts a bit like 'top', listing the NFS clients who made the most NFS
operations every 5 seconds.  Current versions of systemtap should have
IPv4 and IPv6 client support.

I'll be incorporating this into the systemtap examples.

Any feedback on the script would be appreciated.

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)
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#!/usr/bin/stap -v

global nfsops

# Note that this script counts nfsops/client, ignoring the fact
# whether the nfs operation succeeded or not.

probe nfsd.dispatch
{
	nfsops[client_ip] <<< 1
}

probe timer.s(5)
{
	# Clear the screen and print out the header.  Because the
	# 'HOST:PORT' can get quite long for IPv6 (the longest the
	# host:port combination could be is:
	#  [0000:0000:0000:0000:0000:0000:0000:0001]:XXXXXX
	# or 48 chars), we'll print the 'NFS CALLS' first.
	ansi_clear_screen()
	ansi_set_color2(37, 40)
	printf("NFS CALLS   %-48s\n", "HOST:PORT")
	ansi_reset_color()

	# Print out the sorted stats for the top 20 clients.
	foreach ([client_ip] in nfsops- limit 20) {
		printf("%9d   %s\n", @count(nfsops[client_ip]), client_ip)
	}

	# Clear out the array for the next iteration.
	delete nfsops
}

probe begin
{
	printf("gathering NFS data...\n")
}