From: Prarit Bhargava <prarit@redhat.com>
Date: Thu, 23 Oct 2014 18:22:12 +0000 (-0400)
Subject: PCI: Allow numa_node override via sysfs
X-Git-Tag: omap-for-v3.19/fixes-rc1~137^2~1^5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=63692df103e9c76b26c382ce8079283b7df9a99a;p=pandora-kernel.git

PCI: Allow numa_node override via sysfs

NUMA systems with ACPI normally describe the physical topology via _PXM
methods.  But many BIOSes don't implement _PXM, which leaves the kernel
with no way to discover the device topology, which reduces performance
because we can't put memory and processes close to the device.

The NUMA node of a PCI device is already exported in the sysfs "numa_node"
file.  Make that file writable so users can workaround the lack of _PXM
methods in the BIOS.  For example:

  echo 3 > /sys/devices/pci0000:ff/0000:03:1f.3/numa_node

sets the node for PCI device 0000:03:1f.3.

Writing the file emits a FW_BUG warning to encourage users to request
firmware updates.  It also taints the kernel with TAINT_FIRMWARE_WORKAROUND
because overriding the node incorrectly can cause performance issues.

[bhelgaas: changelog, documentation text]
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Myron Stowe <mstowe@redhat.com>
CC: Alexander Ducyk <alexander.h.duyck@redhat.com>
CC: Jiang Liu <jiang.liu@linux.intel.com>
---

Reading git-diff-tree failed