processor-affinity-mask

Arguments:

Windows only.

The processor affinity in Windows is a number which specifies the number of processors (i.e. chips) that will be used by the running process. In Allegro CL 7.0, the best affinity is 1 and there are known problems with higher affinities. The startup code on Windows sets the affinity to 1.

This function is defined on Windows versions only. It uses a Microsoft routine which is documented as working on Windows NT/2000/XP. (On Unix versions, the symbol exists but has no function definition.)

On Windows, return the current process' processor affinity mask (a non-negative integer). It does this by calling GetProcessAffinityMask(), and an error is signaled if this routine returns an error (0).

setf'ing sys:processor-affinity-mask

The setf value is the new processor affinity mask--see the Microsoft documentation on SetProcessAffinityMask(). Our startup code sets the mask to 1 (see the (internal) function start-lisp-execution defined in [Allegro directory]/src/aclstart.cl). An error is signalled if the call to SetProcessAffinityMask() fails.

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Created 2019.8.20.