[fpc-devel] make -j for windows, number of cores?

Reinier Olislagers reinierolislagers at gmail.com
Mon Mar 17 10:42:53 CET 2014

On 17/03/2014 10:36, Marco van de Voort wrote:
> In our previous episode, Reinier Olislagers said:
>>> No. Even not on Windows. You need the number of physical cores, not logical
>>> ones.  This will return the duplicate number of cores on systems with
>>> hyperthreading. (I tested on my system and indeed, 8 instead of 4)
>> Do you see a performance dropoff or instability/crashes... or both when
>> increasing the job number past the amount of physical cores?
> IIRC yes, 5 is still increasing, 6 is lower than 4 or 5. If I boot it up in
> windows, I'll retest.
Ok, thanks.

> The point was more that the autodetection is IMHO still too immature to
> enable by default.
Got it.
It's disabled for now on Windows anyway as fpcup uses make 3.80 by
default to support the 2.6.x series (see Florian's post).

> But those are SSD based values. Increased disk seeking might make it worse
> on HDDs.

Quick test on Linux x64 VM seems to show increasing to 8 (matching my #
of physical cores, no hyperthreading on my CPU) does increase
performance... using the famous unit of time called "number of cups of
coffee I thought I drank while waiting for the compile"

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