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CPUSET(9)		   Kernel Developer's Manual		     CPUSET(9)

NAME
       cpuset(9)  --  CPUSET_T_INITIALIZER,  CPUSET_FSET,  CPU_CLR,  CPU_COPY,
       CPU_ISSET,   CPU_SET,   CPU_ZERO,   CPU_FILL,   CPU_SETOF,   CPU_EMPTY,
       CPU_ISFULLSET,  CPU_FFS,	 CPU_COUNT,  CPU_SUBSET, CPU_OVERLAP, CPU_CMP,
       CPU_OR,	CPU_ORNOT,  CPU_AND,  CPU_ANDNOT,   CPU_XOR,   CPU_CLR_ATOMIC,
       CPU_TEST_CLR_ATOMIC,	    CPU_SET_ATOMIC,	   CPU_SET_ATOMIC_ACQ,
       CPU_TEST_SET_ATOMIC, CPU_AND_ATOMIC, CPU_OR_ATOMIC,  CPU_COPY_STORE_REL
       -- cpuset manipulation macros

SYNOPSIS
       #include	<sys/_cpuset.h>
       #include	<sys/cpuset.h>

       CPUSET_T_INITIALIZER(ARRAY_CONTENTS);

       CPUSET_FSET

       CPU_CLR(size_t cpu_idx, cpuset_t	*cpuset);

       CPU_COPY(cpuset_t *from,	cpuset_t *to);

       bool
       CPU_ISSET(size_t	cpu_idx, cpuset_t *cpuset);

       CPU_SET(size_t cpu_idx, cpuset_t	*cpuset);

       CPU_ZERO(cpuset_t *cpuset);

       CPU_FILL(cpuset_t *cpuset);

       CPU_SETOF(size_t	cpu_idx, cpuset_t *cpuset);

       bool
       CPU_EMPTY(cpuset_t *cpuset);

       bool
       CPU_ISFULLSET(cpuset_t *cpuset);

       int
       CPU_FFS(cpuset_t	*cpuset);

       int
       CPU_COUNT(cpuset_t *cpuset);

       bool
       CPU_SUBSET(cpuset_t *haystack, cpuset_t *needle);

       bool
       CPU_OVERLAP(cpuset_t *cpuset1, cpuset_t *cpuset2);

       bool
       CPU_CMP(cpuset_t	*cpuset1, cpuset_t *cpuset2);

       CPU_OR(cpuset_t *dst, cpuset_t *src1, cpuset_t *src2);

       CPU_ORNOT(cpuset_t *dst,	cpuset_t *src1,	cpuset_t *src2);

       CPU_AND(cpuset_t	*dst, cpuset_t *src1, cpuset_t *src2);

       CPU_ANDNOT(cpuset_t *dst, cpuset_t *src1, cpuset_t *src2);

       CPU_XOR(cpuset_t	*dst, cpuset_t *src1, cpuset_t *src2);

       CPU_CLR_ATOMIC(size_t cpu_idx, cpuset_t *cpuset);

       CPU_TEST_CLR_ATOMIC(size_t cpu_idx, cpuset_t *cpuset);

       CPU_SET_ATOMIC(size_t cpu_idx, cpuset_t *cpuset);

       CPU_SET_ATOMIC_ACQ(size_t cpu_idx, cpuset_t *cpuset);

       CPU_TEST_SET_ATOMIC(size_t cpu_idx, cpuset_t *cpuset);

       CPU_AND_ATOMIC(cpuset_t *dst, cpuset_t *src);

       CPU_OR_ATOMIC(cpuset_t *dst, cpuset_t *src);

       CPU_COPY_STORE_REL(cpuset_t *from, cpuset_t *to);

DESCRIPTION
       The cpuset(9) family of macros provide a	flexible and efficient CPU set
       implementation,	backed	by  the	 bitset(9) macros.  Each CPU is	repre-
       sented by a single bit.	The maximum number of  CPUs  representable  by
       cpuset_t	 is  CPU_SETSIZE.   Individual	CPUs in	cpusets	are referenced
       with indices zero through CPU_SETSIZE - 1.

       The CPUSET_T_INITIALIZER() macro	allows one to  initialize  a  cpuset_t
       with a compile time literal value.

       The  CPUSET_FSET()  macro  defines  a  compile  time literal, usable by
       CPUSET_T_INITIALIZER(), representing a full cpuset (all CPUs  present).
       For examples of CPUSET_T_INITIALIZER() and CPUSET_FSET()	usage, see the
       "CPUSET_T_INITIALIZER EXAMPLE" section.

       The  CPU_CLR()  macro removes CPU cpu_idx from the cpuset pointed to by
       cpuset.	The CPU_CLR_ATOMIC() macro is identical, but  the  bit	repre-
       senting	the  CPU  is  cleared  with  atomic machine instructions.  The
       CPU_TEST_CLR_ATOMIC() macro atomically clears the bit representing  the
       CPU and returns whether it was set.

       The  CPU_COPY()	macro  copies  the  contents of	the cpuset from	to the
       cpuset to.  CPU_COPY_STORE_REL()	is similar, but	copies	component  ma-
       chine  words from from and writes them to to with atomic	store with re-
       lease semantics.	 (That is, if  to  is  composed	 of  multiple  machine
       words, CPU_COPY_STORE_REL() performs multiple individually atomic oper-
       ations.)

       The  CPU_SET()  macro  adds  CPU	 cpu_idx  to  the cpuset pointed to by
       cpuset, if it is	not already present.  The  CPU_SET_ATOMIC()  macro  is
       identical,  but the bit representing the	CPU is set with	atomic machine
       instructions.  The CPU_SET_ATOMIC_ACQ() macro sets the bit representing
       the CPU with atomic acquire semantics.  The CPU_TEST_SET_ATOMIC() macro
       atomically sets the bit representing the	CPU and	returns	whether	it was
       set.

       The CPU_ISSET() macro returns true if CPU cpu_idx is a  member  of  the
       cpuset pointed to by cpuset.

       The CPU_ZERO() macro removes all	CPUs from cpuset.

       The CPU_FILL() macro adds all CPUs to cpuset.

       The CPU_SETOF() macro removes all CPUs in cpuset	before adding only CPU
       cpu_idx.

       The CPU_EMPTY() macro returns true if cpuset is empty.

       The  CPU_ISFULLSET()  macro  returns true if cpuset is full (the	set of
       all CPUs).

       The CPU_FFS() macro returns the 1-index of the first  (lowest)  CPU  in
       cpuset,	or zero	if cpuset is empty.  Like with ffs(3), to use the non-
       zero result of CPU_FFS()	as a cpu_idx  index  parameter	to  any	 other
       cpuset(9) macro,	you must subtract one from the result.

       The CPU_COUNT() macro returns the total number of CPUs in cpuset.

       The CPU_SUBSET()	macro returns true if needle is	a subset of haystack.

       The  CPU_OVERLAP()  macro  returns true if cpuset1 and cpuset2 have any
       common CPUs.  (That is, if cpuset1 AND cpuset2 is not the empty set.)

       The CPU_CMP() macro returns true	if cpuset1 is NOT equal	to cpuset2.

       The CPU_OR() macro adds CPUs  present  in  src  to  dst.	  (It  is  the
       cpuset(9)  equivalent  of  the scalar: dst |= src.)  CPU_OR_ATOMIC() is
       similar,	but sets the bits representing CPUs in the  component  machine
       words  in  dst  with  atomic machine instructions.  (That is, if	dst is
       composed	of multiple machine words, CPU_OR_ATOMIC()  performs  multiple
       individually atomic operations.)

       The CPU_ORNOT() macro add CPUs not in src to dst.  (It is the cpuset(9)
       equivalent of the scalar: dst |=	~ src.)

       The  CPU_AND() macro removes CPUs absent	from src from dst.  (It	is the
       cpuset(9) equivalent of the scalar: dst &= src.)	  CPU_AND_ATOMIC()  is
       similar,	with the same atomic semantics as CPU_OR_ATOMIC().

       The  CPU_ANDNOT()  macro	 removes  CPUs	in  src	 from dst.  (It	is the
       cpuset(9) equivalent of the scalar: dst &= ~ src.)

CPUSET_T_INITIALIZER EXAMPLE
       cpuset_t	myset;

       /* Initialize myset to filled (all CPUs)	*/
       myset = CPUSET_T_INITIALIZER(CPUSET_FSET);

       /* Initialize myset to only the lowest CPU */
       myset = CPUSET_T_INITIALIZER(0x1);

SEE ALSO
       cpuset(1), cpuset(2), bitset(9)

HISTORY
       <sys/cpuset.h> first appeared in	FreeBSD	7.1, released in January 2009,
       and in FreeBSD 8.0, released in November	2009.

       This manual page	first appeared in FreeBSD 11.0.

AUTHORS
       The cpuset(9) macros were written by Jeff Roberson  <jeff@FreeBSD.org>.
       This manual page	was written by Conrad Meyer <cem@FreeBSD.org>.

CAVEATS
       Unlike every other reference to individual set members, which are zero-
       indexed,	 CPU_FFS() returns a one-indexed result	(or zero if the	cpuset
       is empty).

FreeBSD	15.0			August 7, 2025			     CPUSET(9)

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