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From Shawn Heisey <>
Subject Re: UseLargePages
Date Fri, 02 Jan 2015 15:09:24 GMT
On 1/1/2015 10:12 PM, William Bell wrote:
> Do you think setting aside 2GB for UseLargePages would generally help
> indexing or not?
> I can imaging it might help....

Allocating part of your operating system memory as huge pages and then
turning on UseLargePages probably will help with general performance,
though I do not have any hard data.  All indications are that you should
probably turn off the "transparent huge pages" feature in the OS if you
use them, though.

When I did some experimentation with UseLargePages a while back, it made
the operating system lie to me with regard to how much RAM the Solr
process is using.  If you create enough huge pages so that the entire
heap can be allocated from them, then what I have seen is that the OS
will tell you that the resident memory size of the application is only a
few hundred MB, even if you set your min/max heap to several gigabytes.
 This is the case on CentOS 6, with a 2.6.32 kernel.  It's possible that
the OS tools have eliminated that problem since then -- the tools in
that operating system are very old.


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