Difference between revisions of "VSwap"
m (Updated to reflect recent blog post by Kir that kmemsize, dcachesize, and locked pages can be set to unlimited for kernel 042stable042 and later) |
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New [[Download/kernel/rhel6|RHEL6-based OpenVZ]] kernel has a new memory management model, which supersedes [[UBC|User beancounters]]. It is called '''VSwap'''. | New [[Download/kernel/rhel6|RHEL6-based OpenVZ]] kernel has a new memory management model, which supersedes [[UBC|User beancounters]]. It is called '''VSwap'''. | ||
| − | Now you can set two primary parameters: <code>physpages</code> and <code>swappages</code>, while all the other beancounters become secondary. | + | Now you can set two primary parameters: <code>physpages</code> and <code>swappages</code>, while all the other beancounters become secondary and optional. |
* '''physpages''' | * '''physpages''' | ||
: This parameter limits the physical memory (RAM) available to processes inside a container. | : This parameter limits the physical memory (RAM) available to processes inside a container. | ||
| − | : The <code>barrier</code> is ignored, and the <code>limit</code> sets the limit. | + | : The <code>barrier</code> is ignored and should be set to 0, and the <code>limit</code> sets the limit. |
: Currently the user memory and the page cache are accounted into <code>physpages</code>. | : Currently the user memory and the page cache are accounted into <code>physpages</code>. | ||
* '''swappages''' | * '''swappages''' | ||
: This parameter limits the amount of swap space which can be used for processes inside a container. | : This parameter limits the amount of swap space which can be used for processes inside a container. | ||
| − | : The <code>barrier</code> is ignored, and the <code>limit</code> sets the limit. | + | : The <code>barrier</code> is ignored and should be set to 0, and the <code>limit</code> sets the limit. |
The sum of <code>physpages.limit</code> and <code>swappages.limit</code> limits the maximum amount | The sum of <code>physpages.limit</code> and <code>swappages.limit</code> limits the maximum amount | ||
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on the system. | on the system. | ||
| − | === | + | == See also == |
| − | + | * [http://openvz.livejournal.com/39765.html Recent improvements in VSwap]. | |
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[[Category: UBC]] | [[Category: UBC]] | ||
Revision as of 10:36, 10 January 2012
New RHEL6-based OpenVZ kernel has a new memory management model, which supersedes User beancounters. It is called VSwap.
Now you can set two primary parameters: physpages and swappages, while all the other beancounters become secondary and optional.
- physpages
- This parameter limits the physical memory (RAM) available to processes inside a container.
- The
barrieris ignored and should be set to 0, and thelimitsets the limit. - Currently the user memory and the page cache are accounted into
physpages.
- swappages
- This parameter limits the amount of swap space which can be used for processes inside a container.
- The
barrieris ignored and should be set to 0, and thelimitsets the limit.
The sum of physpages.limit and swappages.limit limits the maximum amount
of allocated memory which can be used by a container. When physpages limit
is reached, memory pages belonging to the container are pushed out to
so called virtual swap (vswap). The difference between normal swap
and vswap is that with vswap no actual disk I/O usually occurs. Instead,
a container is artificially slowed down, to emulate the effect of the real
swapping. Actual swap out occurs only if there is a global memory shortage
on the system.
