linux-kernel - Re: [PATCH] x86/PCI: initialize PCI bus node numbers early

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Message-ID: <20090710132249.1a032cfb@jbarnes-g45>
Date:	Fri, 10 Jul 2009 13:22:49 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Jesse Brandeburg <jesse.brandeburg@...il.com>
Subject: Re: [PATCH] x86/PCI: initialize PCI bus node numbers early

On Fri, 10 Jul 2009 13:18:06 -0700
Yinghai Lu <yinghai@...nel.org> wrote:

> Jesse Barnes wrote:
> > The current mp_bus_to_node array is initialized only by AMD specific
> > code, since AMD platforms have registers that can be used for
> > determining mode numbers.  On new Intel platforms it's necessary to
> > initialize this array as well though, otherwise all PCI node numbers
> > will be 0, when in fact they should be -1 (indicating that I/O isn't
> > tied to any particular node).
> > 
> > So move the mp_bus_to_node code into the common PCI code, and
> > initialize it early with a default value of -1.  This may be
> > overridden later by arch code (e.g. the AMD code).
> > 
> > With this change, PCI consistent memory and other node specific
> > allocations (e.g. skbuff allocs) should occur on the "current" node.
> > If, for performance reasons, applications want to be bound to
> > specific nodes, they should open their devices only after being
> > pinned to the CPU where they'll run, for maximum locality.
> > 
> > Any thoughts here Yinghai or Jesse?
> > 
> > 
> >  include/asm/pci.h |    2 +
> >  kernel/setup.c    |    2 +
> >  pci/amd_bus.c     |   61 +-----------------------------------------
> >  pci/common.c      |   77
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 4 files
> > changed, 83 insertions(+), 59 deletions(-)
> > 
> > Thanks,
> 
> could use
> 
> static int mp_bus_to_node[BUS_NR] = {
>         [0 ... BUS_NR - 1] = -1
> };
> 
> so we avoid to add pci_bus_to_node_init()

Ah yeah that would clean things up a bit...  Thanks.

-- 
Jesse Barnes, Intel Open Source Technology Center
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