cpusetCreate(3x) cpusetCreate(3x)
cpusetCreate - create a cpuset
#include <cpuset.h>
int cpusetCreate(char *qname, cpuset_QueueDef_t *qdef);
The cpusetCreate function is used to create a cpuset queue. Only
processes running root user ID are allowed to create cpuset queues.
The qname argument is the name that will be assigned to the new cpuset.
The name of the cpuset must be a three to eight character string. Queue
names having one or two characters are reserved for use by IRIX.
The qdef argument is a pointer to a cpuset_QueueDef_t structure (defined
in <cpuset.h>) that defines the attributes of the queue to be created.
The memory for the cpuset_QueueDef_t is allocated using
cpusetAllocQueueDe
.
The cpuset_QueueDef_t structure is defined as follows:
typedef struct {
int flags;
char *permfile;
cpuset_CPUList_t *cpu;
} cpuset_QueueDef_t;
flags is used to specify various control options for the cpuset queue.
It is formed by OR-ing together zero or more of the following values:
CPUSET_CPU_EXCLUSIVE
Defines a cpuset to be restricted. Only threads attached to the
cpuset queue (descendents of an attached thread inherit the
attachement) may execute on the CPUs contained in the cpuset.
CPUSET_MEMORY_LOCAL
Threads assigned to the cpuset will attempt to assign memory only
from nodes within the cpuset. Assignment of memory from outside
the cpuset will occur only if no free memory is available from
within the cpuset. No restrictions are made on memory assignment
to threads running outside the cpuset.
CPUSET_MEMORY_EXCLUSIVE
Threads assigned to the cpuset will attempt to assign memory only
from nodes within the cpuset. Assignment of memory from outside
the cpuset will occur only if no free memory is available from
within the cpuset. Threads not assigned to the cpuset will not
use memory from within the cpuset unless no memory outside the
cpuset is available. If, at the time a cpuset is created, memory
is already assigned to threads that are already running, no
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cpusetCreate(3x) cpusetCreate(3x)
attempt will be made to explicitly move this memory. If page
migration is enabled, the pages will be migrated when the system
detects that most references to the pages are non-local.
CPUSET_MEMORY_KERNEL_AVOID
The kernel should attempt to avoid allocating memory from nodes
contained in this cpuset. If kernel memory requests cannot be
satisfied from outside this cpuset, this option will be ignored
and allocations will occur from within the cpuset. (This avoidance
currently extends only to keeping buffer cache away from the
protected nodes.)
CPUSET_MEMORY_MANDATORY
The kernel will limit all memory allocations to nodes that are
contained in this cpuset. If memory requests cannot be satisfied,
the allocating process will sleep until memory is available. The
process will be killed if no more memory can be allocated. See
policies below.
CPUSET_POLICY_PAGE
Requires MEMORY_MANDATORY. This is the default policy if no policy
is specified. This policy will cause the kernel to page user pages
to the swap file (see swap(1M)) to free physical memory on the
nodes contained in this cpuset. If swap space is exhausted, the
process will be killed.
CPUSET_POLICY_KILL
Requires MEMORY_MANDATORY. The kernel will attempt to free as much
space as possible from kernel heaps, but will not page user pages
to the swap file. If all physical memory on the nodes contained
in this cpuset are exhausted, the process will be killed.
The permfile member is the name of the file that defines the access
permissions for the cpuset queue. The file permissions of filename
referenced by permfile define access to the cpuset. Every time
permissions need to be checked, the current permissions of this file are
used. Thus, it is possible to change the access to a particular cpuset
without having to tear it down and recreate it, simply by changing the
access permissions. Read access to the permfile allows a user to
retrieve information about a cpuset, while execute permission allows the
user to attach a process to the cpuset.
The cpu member is a pointer to a cpuset_CPUList_t structure. The memory
for the cpuset_CPUList_t structure is allocated and released when the
cpuset_QueueDef_t structure is allocated and released (see
cpusetAllocQueueDef(3x)). The cpuset_CPUList_t structure contains the
list of CPUs assigned to the cpuset. The cpuset_CPUList_t structure
(defind in <cpuset.h>) is defined as follows:
typedef struct {
int count;
int *list;
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cpusetCreate(3x) cpusetCreate(3x)
} cpuset_CPUList_t;
The count member defines the number of CPUs contained in the list.
The list member is pointer to the list (an allocated array) of the CPU
IDs. The memory for the list array is allocated and released when the
cpuset_CPUList_t structure is allocated and released.
This example creates a cpuset queue that has access controled by the file
/usr/tmp/mypermfile, contains CPU IDs 4, 8, and 12, is CPU exclusive and
memory exclusive:
cpuset_QueueDef_t *qdef;
char *qname = "myqueue";
/* Alloc queue def for 3 CPU IDs */
qdef = cpusetAllocQueueDef(3);
if (!qdef) {
perror("cpusetAllocQueueDef");
exit(1);
}
/* Define attributes of the cpuset */
qdef->flags = CPUSET_CPU_EXCLUSIVE
| CPUSET_MEMORY_EXCLUSIVE;
qdef->permfile = "/usr/tmp/mypermfile"
qdef->cpu->count = 3;
qdef->cpu->list[0] = 4;
qdef->cpu->list[1] = 8;
qdef->cpu->list[2] = 12;
/* Request that the cpuset be created */
if (!cpusetCreate(qname, qdef)) {
perror("cpusetCreate");
exit(1);
}
cpusetFreeQueueDef(qdef);
cpusetCreate is found in the library "libcpuset.so", and will be loaded
if the option -lcpuset is used with cc(1) or ld(1).
cpuset(1), cpusetAllocQueueDef(3x), cpusetFreeQueueDef(3x). cpuset(5).
If successful, cpusetCreate returns a 1. If cpusetCreate fails, it
returns the value 0 and errno is set to indicate the error. The possible
values for errno include those values set by fopen(3S), sysmp(2), and the
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cpusetCreate(3x) cpusetCreate(3x)
following:
ENODEV [Toc] [Back]
Request for CPU IDs that do not exist on the system.
EPERM [Toc] [Back]
Request for CPU 0 as part of an exclusive cpuset is not permitted.
PPPPaaaaggggeeee 4444 [ Back ]
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