[xdebug-general] Re: Cachegrind format

On Thu, 19 Feb 2009, Tom Walter wrote:

> A couple of questions about cachegrind files.
>
> I get the impression that the xdebug cachegrind files cannot show memory
> information, although I've never seen anyone outright say that. Why is this,
> and is it something that is planned to be fixed?

The way how cachegrind handles aggregation doesn't work well with how
memory profiling works unfortunately.

> Also exactly what are the numbers in the cachegrind files? The 'events' header
> of the cachegrind file labels them 'Time', but this doesn't tell me much, they
> are not milliseconds, perhaps they are clock ticks? But if so, why doesn't the
> header say 'ticks'.

They're microseconds, if I recall correctly.

> I use wincachegrind and that interprets them as milliseconds, but that
> doesn't seem right at all, because if I try and correlate the times
> with the data output in an xdebug trace file, it doesn't match up at
> all.

Remember that the profiler tries not to include information about the
time that it takes PHP to call a specific function — so this could be a
point of difference.

regards,
Derick

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