kernel-packages team mailing list archive

Thread
Date

[Bug 1401150] Re: Endianness issue in the VPHN topology update code

To: kernel-packages@xxxxxxxxxxxxxxxxxxx
From: Brad Figg <brad.figg@xxxxxxxxxxxxx>
Date: Fri, 19 Dec 2014 17:38:53 -0000
Reply-to: Bug 1401150 <1401150@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

This bug is awaiting verification that the kernel in -proposed solves
the problem. Please test the kernel and update this bug with the
results. If the problem is solved, change the tag 'verification-needed-
trusty' to 'verification-done-trusty'.

If verification is not done by 5 working days from today, this fix will
be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how
to enable and use -proposed. Thank you!


** Tags added: verification-needed-trusty

** Tags added: verification-needed-utopic

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1401150

Title:
  Endianness issue in the VPHN topology update code

Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Trusty:
  Fix Committed
Status in linux source package in Utopic:
  Fix Committed

Bug description:
  SRU Justification:

  [Impact]
  The current VPHN code assumes the NUMA toplogy updates data are big endian. They are native endian actually since the hypervisor pass them through registers. This has a great performance impact on little endian guests.

  [Test Case]
  Install NUMA capable power8 machine in LE mode, install LE guest. Measure performance differences in LE guest after applying this patch.

  [Fix]
  commit 5c9fb1899400096c6818181c525897a31d57e488 upstream
  in v3.18-rc2

  A fix has been sent to fix the issue:

  http://patchwork.ozlabs.org/patch/396171/

  Please pick the following commit from Michael Ellermans's tree:

  http://git.kernel.org/cgit/linux/kernel/git/mpe/linux.git/commit/?id=5c9fb1899400096c6818181c525897a31d57e488

  which reads: "powerpc/vphn: NUMA node code expects big-endian"

  Now upstream:

  commit 5c9fb1899400096c6818181c525897a31d57e488
  Author: Greg Kurz <gkurz@xxxxxxxxxxxxxxxxxx>
  Date:   Wed Oct 15 12:42:58 2014 +0200

      powerpc/vphn: NUMA node code expects big-endian

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1401150/+subscriptions