Re: Tips regarding measuring function execution times

[Helge Kruse <Helge.Kruse () gmx net>]

Hi Paul,

If you are working in Windows environment you can use
QueryPerformanceCounter (QPC) to get a high resolution time value. The
actual time resolution might vary, use QueryPerfomanceFrequency to get
the resolution. At my Windows 10 system I get a frequency of 3914059,
i.e. ~250ns.

But there is no C++ interface necessary tp Access QPC/QPF.
(https://msdn.microsoft.com/en-us/library/windows/desktop/ms644904(v=vs.85).aspx)

See also: https://msdn.microsoft.com/en-us/library/windows/desktop/dn553408(v=vs.85).aspx

Regards
Helge

2017-10-16 8:34 GMT+02:00 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>
> wrote:
>
> Thanks to all for the tips.  I’ll give it a go.
>
>
>
> From: Wireshark-dev [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>
> 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>:
>
>
>
> 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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