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I have CentOS 5.5 and this is my kernel: 2.6.18-194.11.1.el5.centos.plusxen
Regulary, my comuter have ~2G of memory. After creating Xen DomUs (2 domains 512 M memory each one) it down to ~1G, but it does not return to 2G even after all domains go sleep.

So, this is MemTotal line from /proc/meminfo directly after Dom0 boot:

MemTotal:      1777664 kB

And this is after I boot up and boot down 2 DomUs:

MemTotal:       980992 kB

This is output of xm list after I put domains down:

[~]# xm list
Name                                      ID Mem(MiB) VCPUs State   Time(s)
Domain-0                                   0      958     2 r-----   1819.9

What I need for return the memory to Dom0?

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migrated from Aug 24 '10 at 13:08

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up vote 2 down vote accepted

Xen does not automatically reallocate memory to domain 0 once a domU has shut down. You will need to use xm mem-set to reallocate it manually.

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Thank you very much! It works. I only want to add for people who will read this, that domain id and memory in megabytes must be supplied after mem-set subcommand, and that maxmem value from output of xm list -l 0 (for Dom0) can be used. – Rodnower Aug 24 '10 at 17:56

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