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

Reinier Olislagers reinierolislagers at gmail.com
Mon Mar 17 10:23:02 CET 2014

On 16/03/2014 19:45, Marco van de Voort wrote:
> In our previous episode, Reinier Olislagers said:
>> The build faq (that I have) states:
>> 1. Does make -j work reliably on Windows, too?
>> 2. I intend to detect the number of logical cores as per
>> http://wiki.lazarus.freepascal.org/Example_of_multi-threaded_application:_array_of_threads#1._Detect_number_of_cores_available.
>> and run that many jobs. Is that a good idea?
> 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?

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