[Bug 1068199] Re: please add support for MAP_HUGETLB in eglibc for Lucid

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: eglibc (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1068199

Title:
  please add support for MAP_HUGETLB in eglibc for Lucid

Status in “eglibc” package in Ubuntu:
  Confirmed
Status in “eglibc” source package in Lucid:
  In Progress

Bug description:
  it looks like eglibc on 10.04 does not have MAP_HUGETLB headers or
  flags activated [1].

  According to hugetlbpage.txt [2] they state that if the application is making use of only (shmget, shmat) calls you don't really
  need a virtual filesystem. This behaviout *DOES NOT* happen on 10.04 using the released hugepages 10.04 packages but it DOES WORK when using precise packages.

  [Impact]
  Those wishing utilize hugepages on Lucid.

  [Test Case]
  Here are some steps to reproduce the issue.

  1. Configure hugepages with filesystem support.
  2. Test and validate that it works with 10.04 packages.
  3. Umount the virtual filesystem
  sudo umount /mnt/hugetlbfs
  4. run:
  LD_PRELOAD=libhugetlbfs.so HUGETLB_MORECORE=yes ls /boot
  You will get the following error message:
  libhugetlbfs: WARNING: Hugepage size 2097152 unavailable
  abi-2.6.32-43-server grub lost+found System.map-2.6.32-43-server vmlinuz-2.6.32-43-server

  5. Download hugepages packages from:
  https://launchpad.net/ubuntu/+source/libhugetlbfs/2.11-0ubuntu1/+build/2263743 and install them.

  6. Try again. It should work without having to configure a virtual
  filesystem.

  [1] - http://old.nabble.com/Missing-MAP_HUGETLB-flag-from-glibc-headers-td30201924.html
  [2] - http://www.kernel.org/doc/Documentation/vm/hugetlbpage.txt

  Leonardo Borda

  [Regressioni Potential]
  Huge page support is already in the kernel so this impact is merely making use of that functionality. There should be no changes needed in current applications since hugepages can be used through existing shmget,shmat routines.

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