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On vertical polarization, kernel can be adjusting CPU capacities dynamically, and cpuplugd can interfere this with hotplug operations causing performance degradation. To prevent this, check if system has switched its polarization state, and act accordingly. If system is on vertical polarization when daemon starts, no CPU hotplug action is triggered. If system changes to vertical polarization during daemon runtime, revert cpuhotplug adjustments and stop further CPU hotplug actions. If system switches back to horizontal polarization during runtime of the daemon, start evaluating CPU hotplug rules and trigger adjustments. Reviewed-by: Steffen Eiden <seiden@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Mete Durlu <meted@linux.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
68 lines
1.9 KiB
Groff
68 lines
1.9 KiB
Groff
.\" Copyright 2017 IBM Corp.
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.\" s390-tools is free software; you can redistribute it and/or modify
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.\" it under the terms of the MIT license. See LICENSE for details.
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.\"
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.TH CPUPLUGD 8 "May 2011" "s390-tools"
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.
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.SH NAME
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cpuplugd \- Linux on System z CPU and memory hotplug daemon
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.
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.SH SYNOPSIS
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.B cpuplugd
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.RI [ OPTIONS ]
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.
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.SH DESCRIPTION
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The cpuplugd daemon dynamically enables and disables CPUs and increases or
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decreases the cooperative memory management (CMM) page pool based on a set of
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rules.
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When the daemon is stopped, the size of the CMM page pool and the number
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of active CPUs are reset to the values they had before the cpuplugd was started.
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This program can be used to control the number of CPUs for Linux on z/VM
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and for Linux in LPAR mode. The memory hotplug feature (CMM page pool) applies
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to Linux on z/VM only.
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The cpuplugd daemon stops any CPU hot-plug operations when the system switches
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to vertical polarization, thus avoiding possible performance penalties.
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.
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.SH OPTIONS
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.TP
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\fB\-c\fP or \fB\-\-config\fP \fI<configuration file>\fP
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Specify the absolute path to the configuration file. This option is mandatory.
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The default configuration file can be found in /etc/cpuplugd.conf.
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.
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.TP
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\fB\-f\fP or \fB\-\-foreground\fP
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Run in the foreground and not as daemon. If this option is
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omitted, the program runs in the background.
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.
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.TP
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\fB\-h\fP or \fB\-\-help\fP
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Print usage message and exit.
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.
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.TP
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\fB\-v\fP or \fB\-\-version\fP
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Print Version information and exit.
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.
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.TP
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\fB\-V\fP or \fB\-\-verbose\fP
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Print verbose messages to stdout (when running in foreground)
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or to syslog otherwise.
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This options is mainly used for debugging purposes.
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.
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.SH EXAMPLES
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To test a setup start cpuplugd in foreground mode using verbose output:
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.br
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.RS 4
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cpuplugd \-V \-f \-c /etc/cpuplugd.conf
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.RE
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For daemon mode, start cpuplugd from an init script as follows:
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.br
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.RS 4
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cpuplugd \-c /etc/cpuplugd.conf
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.RE
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.SH SEE ALSO
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.BR cpuplugd.conf (5)
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