kernel-packages team mailing list archive

[Julian Taylor <jtaylor.debian@xxxxxxxxxxxxxx>]

@Todd
are you sure they are not swappable?
according to lwn they are:
http://lwn.net/Articles/423584/
"""
This scheme will increase the use of huge pages transparently, but it does not yet solve the whole problem. Huge pages must be swappable, lest the system run out of memory in a hurry. Rather than complicate the swapping code with an understanding of huge pages, Andrea simply splits a huge page back into its component small pages if that page needs to be reclaimed. Many other operations (mprotect(), mlock(), ...) will also result in the splitting of a page.
"""

also the performance regression might be fixed in 3.11;
http://kernel.opensuse.org/cgit/kernel/commit/?id=348944504362417205107e63cfe4821aa87ec1bb
mm: fix aio performance regression for database caused by THP

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https://bugs.launchpad.net/bugs/743688

Title:
  Transparent HugePages not enabled in 11.04 kernel

Status in “linux” package in Ubuntu:
  Confirmed

Bug description:
  Transparent hugepages, which is a major performance enhancement in the
  2.6.38 kernel is not enabled in the 11.04 kernel.:

  $ cat /etc/issue 
  Ubuntu natty (development branch) \n \l

  $ grep TRANSPARENT /boot/config-2.6.38-7-server
  # CONFIG_TRANSPARENT_HUGEPAGE is not set
  $ grep TRANSPARENT /boot/config-2.6.38-7-generic
  # CONFIG_TRANSPARENT_HUGEPAGE is not set
  $ 

  If this is the way 11.04 kernels will be built, it's a bummer.

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