| .TH CHCPU 8 "July 2014" "util-linux" "System Administration" |
| .SH NAME |
| chcpu \- configure CPUs |
| .SH SYNOPSIS |
| .B chcpu |
| .BR \-c | \-d | \-e | \-g |
| .I cpu-list |
| .br |
| .B chcpu \-p |
| .I mode |
| .br |
| .B chcpu |
| .BR \-r | \-h | \-V |
| .SH DESCRIPTION |
| .B chcpu |
| can modify the state of CPUs. It can enable or disable CPUs, scan for new |
| CPUs, change the CPU dispatching |
| .I mode |
| of the underlying hypervisor, and request CPUs from the hypervisor |
| (configure) or return CPUs to the hypervisor (deconfigure). |
| .PP |
| Some options have a |
| .I cpu-list |
| argument. Use this argument to specify a comma-separated list of CPUs. The |
| list can contain individual CPU addresses or ranges of addresses. For |
| example, |
| .B 0,5,7,9-11 |
| makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10, |
| and 11. |
| .SH OPTIONS |
| .TP |
| .BR \-c , " \-\-configure " \fIcpu-list\fP |
| Configure the specified CPUs. Configuring a CPU means that the hypervisor |
| takes a CPU from the CPU pool and assigns it to the virtual hardware on which |
| your kernel runs. |
| .TP |
| .BR \-d , " \-\-disable " \fIcpu-list\fP |
| Disable the specified CPUs. Disabling a CPU means that the kernel sets it |
| offline. |
| .TP |
| .BR \-e , " \-\-enable " \fIcpu-list\fP |
| Enable the specified CPUs. Enabling a CPU means that the kernel sets it |
| online. A CPU must be configured, see \fB\-c\fR, before it can be enabled. |
| .TP |
| .BR \-g , " \-\-deconfigure " \fIcpu-list\fP |
| Deconfigure the specified CPUs. Deconfiguring a CPU means that the |
| hypervisor removes the CPU from the virtual hardware on which the Linux |
| instance runs and returns it to the CPU pool. A CPU must be offline, see |
| \fB\-d\fR, before it can be deconfigured. |
| .TP |
| .BR \-p , " \-\-dispatch " \fImode\fP |
| Set the CPU dispatching |
| .I mode |
| (polarization). This option has an effect only if your hardware architecture |
| and hypervisor support CPU polarization. Available |
| .I modes |
| are: |
| .RS 14 |
| .TP 12 |
| .PD 0 |
| .B horizontal |
| The workload is spread across all available CPUs. |
| .TP 12 |
| .B vertical |
| The workload is concentrated on few CPUs. |
| .RE |
| .PD 1 |
| .TP |
| .BR \-r , " \-\-rescan" |
| Trigger a rescan of CPUs. After a rescan, the Linux kernel recognizes |
| the new CPUs. Use this option on systems that do not |
| automatically detect newly attached CPUs. |
| .TP |
| .BR \-V , " \-\-version" |
| Display version information and exit. |
| .TP |
| .BR \-h , " \-\-help" |
| Display help text and exit. |
| |
| .SH RETURN CODES |
| .B chcpu |
| has the following return codes: |
| .TP |
| .BR 0 |
| success |
| .TP |
| .BR 1 |
| failure |
| .TP |
| .BR 64 |
| partial success |
| .RE |
| .SH AUTHOR |
| .MT heiko.carstens@de.ibm.com |
| Heiko Carstens |
| .ME |
| .SH COPYRIGHT |
| Copyright IBM Corp. 2011 |
| .br |
| .SH "SEE ALSO" |
| .BR lscpu (1) |
| .SH AVAILABILITY |
| The chcpu command is part of the util-linux package and is available from |
| .UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ |
| Linux Kernel Archive |
| .UE . |
