Resource shortage - Revision history

Kir: /* cpuunits */ intentation

2013-10-08T19:34:53Z

‎cpuunits: intentation

2012-01-12T20:52:35Z

usage of vzcpucheck explained by kir

2011-04-12T11:49:02Z

‎Disk quota

2011-01-21T10:49:52Z

no longer a stub

2011-01-21T10:31:48Z

‎cpulimit

2010-03-12T18:13:29Z

2009-03-21T10:04:11Z

Additional explanation of cpulimit on multi-core servers.

2009-03-06T09:06:06Z

‎cpulimit: warn -> warning

2008-09-09T19:22:25Z

subsections of ‎CPU: ; warn about cpulimit not working in devel kernels

2008-09-05T14:06:44Z

@@ Line 142: / Line 142: @@
 Add the three units, 1000+2000+3000 = 6000
-gets 1000/6000 or 1/6th of the time. (16%)
+* 101 gets 1000/6000 or 1/6th of the time. (16%)
-gets 2000/6000 or 1/3rd of the time. (34%)
+* 102 gets 2000/6000 or 1/3rd of the time. (34%)
-gets 3000/6000 or 1/2 of the time.   (50%)
+* 103 gets 3000/6000 or 1/2 of the time.   (50%)
 To summarize: those units are proportional to each other. To say it more strict, to the sum of all CTs units, plus the host system, please don't forget that one. So indeed, units of 1 1 1 1 are the same as 200 200 200 200 or 8888 8888 8888 8888.

@@ Line 145: / Line 145: @@
 gets 2000/6000 or 1/3rd of the time. (34%)
 gets 3000/6000 or 1/2 of the time.   (50%)
 === cpulimit ===

← Older revision		Revision as of 11:49, 12 April 2011
Line 111:		Line 111:
	</ol>		</ol>

		+	Applying a different diskinodes configuration is applied instantly and does not require a restart of the container.
		+
		+	You can also find the number of free inodes with
		+
		+	<pre>
		+	# vzctl exec 123 df -i
		+	</pre>
	{{Note\|shell does not support floating-point arithmetic, i.e. you can not use expressions like <code>$(( 2200001.5 ))</code>. To use floating point, try <code>bc</code> instead, something like this: <code><nowiki>$(echo 2200001.5 \| bc)</nowiki></code>.}}		{{Note\|shell does not support floating-point arithmetic, i.e. you can not use expressions like <code>$(( 2200001.5 ))</code>. To use floating point, try <code>bc</code> instead, something like this: <code><nowiki>$(echo 2200001.5 \| bc)</nowiki></code>.}}

← Older revision		Revision as of 10:49, 21 January 2011
Line 152:		Line 152:

	In the rhel6 kernel the applied limit is divided between onlince CPUs proportionally and a busy CPU cannot borrow time from an idle one. I.e. with a 2 CPUs container and 100% limit set the usage of each CPU cannot exceed 50% in any case.		In the rhel6 kernel the applied limit is divided between onlince CPUs proportionally and a busy CPU cannot borrow time from an idle one. I.e. with a 2 CPUs container and 100% limit set the usage of each CPU cannot exceed 50% in any case.
−
−	~~{{Stub}}~~

	[[Category: Troubleshooting]]		[[Category: Troubleshooting]]

@@ Line 147: / Line 147: @@
 says that container 101 cannot ever have more than 25 percent of a CPU even if the CPU is idle for the other 75% of the time. The limit is calculated as a percentage of a single CPU, not as a percentage of the server's CPU resources as a whole. In other words, if you have more than one CPU, you can set a cpulimit > 100. In a quad-core server, setting cpulimit to 100 permits a container to consume one entire core (and not 100% of the server).
-{{Warning|cpulimit is not yet implemented in kernels > 2.6.18 (i.e. development ones). Use stable kernel if you want this feature.}}
+CPU limits are only available in rhel5-based and rhel6-based kernels and they behave a bit differently in them.
 {{Stub}}

@@ Line 90: / Line 90: @@
 vzctl set 123 --diskspace $(( 1048576*2 )):$(( 1153434*2 )) --save
 </pre>
 </li>

@@ Line 133: / Line 133: @@
 vzctl set 101 --cpulimit 25 --save
 </pre>
-says that container 101 cannot ever have more than 25 percent of the cpu even if the cpu is idle for the other 75% of the time.
+says that container 101 cannot ever have more than 25 percent of a CPU even if the CPU is idle for the other 75% of the time. The limit is calculated as a percentage of a single CPU, not as a percentage of the server's CPU resources as a whole. In other words, if you have more than one CPU, you can set a cpulimit > 100. In a quad-core server, setting cpulimit to 100 permits a container to consume one entire core (and not 100% of the server).
 {{Warning|cpulimit is not yet implemented in kernels > 2.6.18 (i.e. development ones). Use stable kernel if you want this feature.}}

@@ Line 105: / Line 105: @@
 There are two parameters controlling fair CPU scheduler in OpenVZ: cpuunits and cpulimit.
 Cpuunits are set via
 <pre>
@@ Line 118: / Line 119: @@
 </pre>
-If we started a cpu intensive application on each VE, then 103 would be given 3 times as much cpu time as 101 and 102 would get twice as much as 101, but some fraction of what 103 got.  Here's how to determine what the real ratios are.
+If we started a CPU intensive application on each CT, then 103 would be given 3 times as much cpu time as 101 and 102 would get twice as much as 101, but some fraction of what 103 got.  Here's how to determine what the real ratios are.
 Add the three units, 1000+2000+3000 = 6000
@@ Line 126: / Line 127: @@
 gets 3000/6000 or 1/2 of the time.   (50%)
-CPULIMIT
+=== cpulimit ===
 The cpulimit parameter sets the absolute maximum limit for a container to a percent value.  For instance:
@@ Line 133: / Line 134: @@
 </pre>
 says that container 101 cannot ever have more than 25 percent of the cpu even if the cpu is idle for the other 75% of the time.
 {{Stub}}