Frank Ch. Eigler wrote:
Mike Mason <[email protected]> writes:
Here's a variation of Jose's script that uses the networking tapset
and prints top-like output for transmits and receives. [...]
Thanks for posting it to the systemtap wiki.
Some minor style suggestions follow:
[...]
ifxmit_p[pid(), dev_name] ++
ifxmit_b[pid(), dev_name] += length
These could be collapsed into a single statistics-aggregate array:
# ifxmit[pid(), dev_name] <<< length
Then the printing routine would use @count(ifxmit[...]) and @sum(ifxmit[...])
to extract the two values. Same of course for ifrecv.
I tried that and got the following output:
PID UID DEV XMIT_PK RECV_PK XMIT_KB RECV_KB COMMAND
0 0 eth0 9 10 486 672 swapper
ERROR: empty aggregate near identifier 'execname' at nettop.stp:35:4
WARNING: Number of errors: 1, skipped probes: 0
Apparently using @sum on empty aggregates isn't allowed. I expected 0's to
be returned. The only way to avoid the error is use @sum only if @count >
0, which makes the printf too complex in my opinion.
execname[pid()] = execname()
user[pid()] = uid()
ifdevs[pid(), dev_name] = dev_name
Calling pid() so many times is worse than calling it once and caching
the result in a local variable ("p = pid()").
Agreed. I'll change that.
The way that the script tracks pid-to-uid and pid-to-execname mappings
is not bad, though if that part were moved to new probes on fork or
exec, it would allow the network-related probes to run concurrently on
an SMP without fighting over locks.
But that would only catch processes created after the script starts, correct?
- Mike
- FChE
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