Re: The cost of memory allocation

[Graham Bloice <graham.bloice () trihedral com>]

On 21 September 2016 at 09:29, Paul Offord <Paul.Offord () advance7 com> wrote:

> I’m not happy with the performance of the transum dissector and so I’ve
> started some analysis.  I’ve never used VS performance profiling before but
> I plan try to investigate this problem using it.  In the meantime I’ve used
> a tool that I’m reasonably familiar with called PerfView.  It’s produced
> some interesting results which I thought I’d share.
>
>
>
> The problem I’m having is that with transum enabled load time for a 50MB
> file increases from 5 seconds to 10 seconds, but then subsequent loads of
> the same file go out to about 40 or 50 seconds.
>
>
>
>
>
> Above (or attached depending on your email system) is a screen shot
> showing the time spent in various functions when a load of the file took
> 44.8 seconds.  At the top of the image is a transum function called
> decode_gtcp.  The image shows that 50.7% of the total load time was spent
> executing in this function.  Then we see all of the nested functions with
> the proportion of time spent in each of those.
>
>
>
> What I notice is that a lot of time is being spent in glib functions, and
> in particular the time is being spent allocating and freeing memory.
>
>
>
>
>
> Using a slightly different view we can see that across the whole of the
> process during a load file with transum enabled more than 66% of the time
> is spent messing around with memory.
>
>
>
> I haven’t yet figured out why I get inconsistent load times, and I don’t
> know what I can do about any of the above, but I thought it might be of
> general interest.
>
>
>
> Best regards…Paul
Release or debug build?

-- 
Graham Bloice

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