Fairsched API - Revision history

Kir: Reverted edits by GenieReddicks (Talk) to last revision by Kir

2011-03-29T10:24:11Z

Reverted edits by GenieReddicks (Talk) to last revision by Kir

GenieReddicks: /* Description */

2011-03-29T10:14:59Z

‎Description

Kir: added Category: Resource management

2011-01-25T09:54:17Z

added Category: Resource management

Kir: VE -> CT; use third-level headings; remove double empty lines; other minor fixes

2011-01-25T09:52:22Z

VE -> CT; use third-level headings; remove double empty lines; other minor fixes

Show changes

Kir: added Category: Kernel

2011-01-25T09:42:48Z

added Category: Kernel

Vdavydov at 08:46, 25 January 2011

2011-01-25T08:46:31Z

Vdavydov at 08:43, 25 January 2011

2011-01-25T08:43:43Z

Vdavydov at 08:34, 25 January 2011

2011-01-25T08:34:54Z

Vdavydov at 07:47, 25 January 2011

2011-01-25T07:47:38Z

Vdavydov at 06:25, 25 January 2011

2011-01-25T06:25:45Z

@@ Line 13: / Line 13: @@
 === Description ===
-The CPU weight defines how much CPU time a CT gets. [http://www.top5optimizers.com speed optimizer] The smaller the weight is, the more CPU time the container gets. The CPU weight is a relative parameter. That means that multiplying the weight of all running CTs by the same value does not change the CPU time distribution. The minimal value of the weight is 1, and the maximal value is <code>FSCHWEIGHT_MAX</code> (65535). The weight of a newly created CT is set to 500 by default.
+The CPU weight defines how much CPU time a CT gets. The smaller the weight is, the more CPU time the container gets. The CPU weight is a relative parameter. That means that multiplying the weight of all running CTs by the same value does not change the CPU time distribution. The minimal value of the weight is 1, and the maximal value is <code>FSCHWEIGHT_MAX</code> (65535). The weight of a newly created CT is set to 500 by default.
 The <code>fairsched_chwt()</code> system call sets the CPU weight of a CT. <code>id</code> is the id of the CT. <code>wght</code> is the desired weight.

@@ Line 13: / Line 13: @@
 === Description ===
-The CPU weight defines how much CPU time a CT gets. The smaller the weight is, the more CPU time the container gets. The CPU weight is a relative parameter. That means that multiplying the weight of all running CTs by the same value does not change the CPU time distribution. The minimal value of the weight is 1, and the maximal value is <code>FSCHWEIGHT_MAX</code> (65535). The weight of a newly created CT is set to 500 by default.
+The CPU weight defines how much CPU time a CT gets. [http://www.top5optimizers.com speed optimizer] The smaller the weight is, the more CPU time the container gets. The CPU weight is a relative parameter. That means that multiplying the weight of all running CTs by the same value does not change the CPU time distribution. The minimal value of the weight is 1, and the maximal value is <code>FSCHWEIGHT_MAX</code> (65535). The weight of a newly created CT is set to 500 by default.
 The <code>fairsched_chwt()</code> system call sets the CPU weight of a CT. <code>id</code> is the id of the CT. <code>wght</code> is the desired weight.

← Older revision		Revision as of 09:54, 25 January 2011
Line 138:		Line 138:

	[[Category: Kernel]]		[[Category: Kernel]]
		+	[[Category: Resource management]]

@@ Line 2: / Line 2: @@
 The '''Fairsched API''' is the set of system calls that can be used (and that are, in fact, used in the <code>vzctl</code> utility) for altering various parameters of the [[CPU Fair scheduler]], such as <code>cpuunits</code>, <code>cpulimit</code>, <code>cpus</code>, and <code>cpumask</code>. The article is targeted at describing the API.
 == CPU weight ==
@@ Line 140: / Line 139: @@
 The parameter is available since the rhel6 kernel.

@@ Line 73: / Line 73: @@
 It is possible to limit the CPU usage of the host system. The host system's id equals <code>INT_MAX</code> (2147483647).
-CPU limits are available only in rhel5-based and rhel6-based kernels, and they behave a bit differently in them in respect of distributing the CPU time among CPUs the VE can execute on.
+CPU limits are available only in rhel5-based and rhel6-based kernels, and they behave a bit differently in them in respect of distributing CPU time among CPUs the VE can execute on.
 In the rhel5 kernel the limit has a container-wide meaning. For example, if there are 2 CPUs available for a container, and the limit is set to 1024 (of 2048), the container's CPU usage can be 100/0%, or 50/50%, or any other values whose sum does not exceed 100%.
@@ Line 79: / Line 79: @@
 In the rhel6 kernel the limit is divided between the CPUs proportionally, and a busy CPU cannot borrow time from an idle one, i.e. with a 2 CPUs container and 1024 (of 2048) limit set the usage of each CPU cannot exceed 50% in any case.
-As a result, the minimal value for the limit is 1 in the rhel5 kernel and 1 * NUM_CPUS in the rhel6 kernel. If the limit value is out of the allowed range it is automatically clamped to the range.
+As a result, the minimal value for the limit is 1 in the rhel5 kernel and 1 * NUM_CPUS in the rhel6 kernel. If the given limit is out of the allowed range it is automatically clamped to the range.

@@ Line 48: / Line 48: @@
 '''Description:'''
-The CPU limit is the upper bound to the CPU usage for a VE. The limit is set for all CPUs the VE can execute on. That means the maximal value of the CPU limit (i.e. no limit) is the maximal limit on 1 CPU, which equals 1024, multiplied by the number of CPUs this VM can execute on. The minimal value is 1. The CPU limit is an absolute parameter in the sense that altering the limit of one VE does not affect the limits of other VEs.
+The CPU limit is the upper bound to the CPU usage for a VE. The limit is set for all CPUs the VE can execute on. That means the maximal value of the CPU limit (i.e. no limit) is the maximal limit on 1 CPU, which equals 1024, multiplied by NUM_CPUS, the number of CPUs this VM can execute on. The CPU limit is an absolute parameter in the sense that altering the limit of one VE does not affect the limits of other VEs.
 The <code>fairsched_rate()</code> system call is used to set, get, or drop (i.e. set to the maximum) CPU limit of a VE. <code>id</code> is the id of the VE. <code>op</code> can be one of the following:
@@ Line 78: / Line 78: @@
 In the rhel6 kernel the limit is divided between the CPUs proportionally, and a busy CPU cannot borrow time from an idle one, i.e. with a 2 CPUs container and 1024 (of 2048) limit set the usage of each CPU cannot exceed 50% in any case.

@@ Line 64: / Line 64: @@
 * <code>EINVAL</code>: <code>id</code>=0.
 * <code>EINVAL</code>: <code>op</code> is invalid.
-* <code>EINVAL</code>: <code>op</code>=<code>FAIRSCHED_SET_RATE</code>, and the value of <code>rate</code> is out of the allowed range.
+* <code>EINVAL</code>: <code>op</code>=<code>FAIRSCHED_SET_RATE</code>, and <code>rate</code><=0.
 * <code>ENOENT</code>: the VE does not exist.
 * <code>ENODATA</code>: <code>op</code>=<code>FAIRSCHED_GET_RATE</code>, and the limit is not set (or was dropped).

← Older revision		Revision as of 06:25, 25 January 2011
Line 1:		Line 1:
	There are several parameters tuning which the OpenVZ administrator can change the CPU usage of a VE. Usually one sets these parameters with the aid of the <code>vzctl</code> utility. But sometimes it can be useful to modify these parameters directly, without using <code>vzctl</code>. For example, it can be required by developers who want to implement an in-place solution to control a particular virtualization system based on OpenVZ. That is why the Fairsched API is introduced.		There are several parameters tuning which the OpenVZ administrator can change the CPU usage of a VE. Usually one sets these parameters with the aid of the <code>vzctl</code> utility. But sometimes it can be useful to modify these parameters directly, without using <code>vzctl</code>. For example, it can be required by developers who want to implement an in-place solution to control a particular virtualization system based on OpenVZ. That is why the Fairsched API is introduced.

−	The '''Fairsched API''' is the set of system calls that can be used (and that are, in fact, used in the <code>vzctl</code> utility) for altering various parameters of the [[CPU Fair scheduler]], such as <code>cpuunits</code>, <code>cpulimit</code>, <code>cpus</code>, and <code>cpumask</code>. The article is targeted ~~to describe~~ the API.	+	The '''Fairsched API''' is the set of system calls that can be used (and that are, in fact, used in the <code>vzctl</code> utility) for altering various parameters of the [[CPU Fair scheduler]], such as <code>cpuunits</code>, <code>cpulimit</code>, <code>cpus</code>, and <code>cpumask</code>. The article is targeted at describing the API.