Intel 64 and IA-32 Architectures Software Developers Manual Volume 3A, System Programming Guide, Part 1

7-46 Vol. 3A
MULTIPLE-PROCESSOR MANAGEMENT
PackageIDBucket is an array of unique PACKAGE_ID values. Allocate an array of
NumStartedLPs count of entries in this array.
PackageProcessorMask is a corresponding array of the bit mask of processors belonging to
the same package, these are processors with the same PACKAGE_ID
The algorithm below assumes there is symmetry across package boundary if more than
one socket is populated in an MP system.
// Bucket Package IDs and compute processor mask for every package.
PackageNum = 1;
PackageIDBucket[0] = PackageID[0];
ProcessorMask = 1;
PackageProcessorMask[0] = ProcessorMask;
For (ProcessorNum = 1; ProcessorNum < NumStartedLPs; ProcessorNum++) {
ProcessorMask << = 1;
For (i=0; i < PackageNum; i++) {
// we may be comparing bit-fields of logical processors residing in different
// packages, the code below assume package symmetry
If (PackageID[ProcessorNum] == PackageIDBucket[i]) {
PackageProcessorMask[i] |= ProcessorMask;
Break; // found in existing bucket, skip to next iteration
}
}
if (i ==PackageNum) {
//PACKAGE_ID did not match any bucket, start new bucket
PackageIDBucket[i] = PackageID[ProcessorNum];
PackageProcessorMask[i] = ProcessorMask;
PackageNum++;
}
}
// PackageNum has the number of Packages started in OS
// PackageProcessorMask[] array has the processor set of each package
c) Using the list of CORE_ID to count the number of cores in a MP system and construct, for each
core, a multi-bit mask corresponding to those logical processors residing in the same core.
Processors in the same core can be determined by bucketing the processors with the same
PACKAGE_ID and CORE_ID. Note that code below can BIT OR the values of PACKGE and CORE ID
because they have not been shifted right.
The algorithm below assumes there is symmetry across package boundary if more than one socket
is populated in an MP system.
//Bucketing PACKAGE and CORE IDs and computing processor mask for every core
CoreNum = 1;
CoreIDBucket[0] = PackageID[0] | CoreID[0];