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Top Forums UNIX for Advanced & Expert Users How to reduce IOWAIT in linux Post 302126788 by bache_gowda on Friday 13th of July 2007 05:18:14 AM
Old 07-13-2007
How to reduce IOWAIT in linux

Hi All,

Any ideas how to reduce IOWAIT and increase disk speed on Linux server.

Server has 4 CPUs and with 8GB RAM.

Thanks in advance,

Regards,
Bache
 

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CHCPU(8)						       System Administration							  CHCPU(8)

NAME
chcpu - configure CPUs SYNOPSIS
chcpu -c|-d|-e|-g cpu-list chcpu -p mode chcpu -r|-h|-V DESCRIPTION
chcpu can modify the state of CPUs. It can enable or disable CPUs, scan for new CPUs, change the CPU dispatching mode of the underlying hypervisor, and request CPUs from the hypervisor (configure) or return CPUs to the hypervisor (deconfigure). Some options have a 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, 0,5,7,9-11 makes the command applicable to the CPUs with the addresses 0, 5, 7, 9, 10, and 11. OPTIONS
-c, --configure cpu-list Configure the specified CPUs. Configuring a CPU means that the hypervisor takes a CPU from the CPU pool and assigns it to the vir- tual hardware on which your kernel runs. -d, --disable cpu-list Disable the specified CPUs. Disabling a CPU means that the kernel sets it offline. -e, --enable cpu-list Enable the specified CPUs. Enabling a CPU means that the kernel sets it online. A CPU must be configured, see -c, before it can be enabled. -g, --deconfigure cpu-list 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 -d, before it can be deconfigured. -p, --dispatch mode Set the CPU dispatching mode (polarization). This option has an effect only if your hardware architecture and hypervisor support CPU polarization. Available modes are: horizontal The workload is spread across all available CPUs. vertical The workload is concentrated on few CPUs. -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 auto- matically detect newly attached CPUs. -V, --version Display version information and exit. -h, --help Display help text and exit. RETURN CODES
chcpu has the following return codes: 0 success 1 failure 64 partial success AUTHOR
Heiko Carstens <heiko.carstens@de.ibm.com> COPYRIGHT
Copyright IBM Corp. 2011 SEE ALSO
lscpu(1) AVAILABILITY
The chcpu command is part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils /util-linux/>. util-linux July 2014 CHCPU(8)
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