Does KSM work with pagecache in RHEL?

Solution Verified - Updated -

Issue

We have some systems that we would like to virtualze with VMWare but we've run into a problem because we are very dependent on the NFS page cache.

We are looking at alternatives, including RHEV. We are interested in whether Kernel SamePage Merging (KSM) can help us with our page cache problem.

The problem is that we have to have a rather large amount of page cache for our application to perform effectively. However allocating that much physical RAM to a guest would really hurt density.

If I had some RHEV guests that were each holding 12GB of page cache, and the page cache was built from the same R/O NFS file system, would KSM successfully merge the page cache down to a de-duplicated 12GB in the host kernel?

Environment

  • Red Hat Enterprise Linux (RHEL) 5, 6

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