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nayabingi 03-29-2011 10:46 AM

Guest Kernel Reserved Memory Very High
Hi all,

I have a 64bit CentOS 5.5 Base VM running on Xen-3.4.2-2.el5. The memory usage seams very high for a idle system. After looking into why I found that the kernel was reserving about 300MB of RAM at boot time. This seams like a large amount and I believe the kernel will not release this RAM that it reserved. Can some tell me why such large amount?

[root@xxxxx ~]# dmesg | grep Memory
Memory: 691316k/16785408k available (2513k kernel code, 356548k reserved, 1399k data, 184k init)

[root@xxxxx ~]# free -m
total used free shared buffers cached
Mem: 1024 581 442 0 34 137
-/+ buffers/cache: 409 614
Swap: 1023 0 1023

Thank you

unSpawn 04-14-2011 12:55 PM

Understanding the Linux Virtual Memory Manager
Linux (the kernel) has a well-performing VMM (virtual memory manager) so unless you use some exotic setup any sysctl values with respect to memory handling do not need tweaking or otherwise dealing with: just let the kernel handle things. Also see Mel Gorman's book "Understanding the Linux Virtual Memory Manager" here:


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