Re: Tips regarding measuring function execution times

[Paul Offord <Paul.Offord () advance7 com>]

Hi Roland,

I’m only doing this for debugging purposes, and I accumulate the total time as each packet is dissected.  To get the 
value as output I’ve put the printf in a cleanup routine that gets triggered when I close the trace file.

Unfortunately, microsecond granularity is not going to do it.  All start and end times produced by the code below are 
equal – giving an elapsed time of zero.  I’ve been looking at Windows nanosecond timers but I’ll have to use C++ to get 
access to those.

Best regards….Paul

From: Wireshark-dev [mailto:wireshark-dev-bounces () wireshark org] On Behalf Of Roland Knall
Sent: 16 October 2017 05:38
To: Developer support list for Wireshark <wireshark-dev () wireshark org>
Subject: Re: [Wireshark-dev] Tips regarding measuring function execution times

Keep in mind, that printf is by far one of the slowest functions. Additionally it slows also down the output as well. 
I'd recommend writing the times into a buffer and dumping them in intervalls, very much like the tap's work, otherwise 
what you see might not be what is happening on the network.

cheers

On Sun, Oct 15, 2017 at 11:15 PM, Paul Offord <Paul.Offord () advance7 com<mailto:Paul.Offord () advance7 com>> wrote:
Thanks to all for the tips.  I’ll give it a go.

From: Wireshark-dev [mailto:wireshark-dev-bounces () wireshark org<mailto:wireshark-dev-bounces () wireshark org>] On 
Behalf Of Pascal Quantin
Sent: 15 October 2017 21:50
To: Developer support list for Wireshark <wireshark-dev () wireshark org<mailto:wireshark-dev () wireshark org>>
Subject: Re: [Wireshark-dev] Tips regarding measuring function execution times



2017-10-15 22:40 GMT+02:00 João Valverde <joao.valverde () tecnico ulisboa pt<mailto:joao.valverde () tecnico ulisboa 
pt>>:


On 15-10-2017 21:32, Peter Wu wrote:
On Sat, Oct 14, 2017 at 02:18:39PM +0000, Paul Offord wrote:
I'm investigating a performance problem with the TRANSUM dissector.  I'd like to measure the accumulated time taken to 
execute a function in a Release build.  My basic idea is to do something like this:

guint32 execute_time_us;
.
.
start_stopwatch(&execute_time_us);
function_call_to_be_measured();
pause_stopwatch(&execute_time_us);

.
.
.

stop_and_output_stopwatch(&execute_time_us);

Is there a standard way to do this in Wireshark?  How can I output the accumulated time on, say, the Status Line?

Not sure about the Status line question, but you can measure elapsed
microseconds with something like:

     guint64 start_time, end_time;

     start_time = g_get_monotonic_time();
     // ...
     end_time = g_get_monotonic_time();
     // ...
     g_print("elapsed us: %" G_GUINT64_FORMAT, end_time - start_time);

https://developer.gnome.org/glib/stable/glib-Date-and-Time-Functions.html#g-get-monotonic-time

I think console output doesn't work on Windows for graphical applications, or something like that. There isn't a better 
standard mechanism for debug output in Wireshark, that I know of.

You can make it appear with Edit -> Preferences -> Advanced -> change gui.console_open option to ALWAYS.

Pascal.

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