8. Configuring and Managing Vector : OS Settings : Using Large Pages : Designate Memory for Huge Pages on Linux
 
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Designate Memory for Huge Pages on Linux
The commands and amounts provided here is an example of designating memory for huge pages on Linux. Before issuing these commands, understand what they do, and adapt the examples, as needed. Reserving pages for use in huge page allocations is system wide, so make sure you are not interfering with other users.
To make 2 GB available for 2 MB huge pages, issue the following commands as root on the command line before starting Vector:
hugeadm --create-global-mounts
hugeadm --pool-pages-min 2M:1024
To switch off, enter the following command as root on the command line:
hugeadm --pool-pages-min 2M:0
To check if memory is allocated for huge pages and how much of it is in use, type at the command line:
cat /proc/meminfo
The information about huge pages is shown in the following example lines:
HugePages_Total:  1024
HugePages_Free:   1024
HugePages_Rsvd:      0
HugePages_Surp:      0
Making memory available for huge pages requires defragmenting the specified amount of memory, so it can take a while. Typically, it is fastest to do this immediately after system startup, when memory is not as fragmented.
For more in-depth information, see the man page of hugeadm, http://linux-mm.org/HugePages, and vm/hugetlbpage.txt in the Linux kernel documentation ( http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/vm/hugetlbpage.txt;hb=HEAD).