Add interleaved NUMA emulation support
This patch interleaves emulated nodes over the system's physical
nodes. This is required for interleave optimizations since
mempolicies, for example, operate by iterating over a nodemask and
act without knowledge of node distances. It can also be used for
testing memory latencies and NUMA bugs in the kernel.
There're a couple of ways to do this:
- divide the number of emulated nodes by the number of physical
nodes and allocate the result on each physical node, or
- allocate each successive emulated node on a different physical
node until all memory is exhausted.
The disadvantage of the first option is, depending on the asymmetry
in node capacities of each physical node, emulated nodes may
substantially differ in size on a particular physical node compared
to another.
The disadvantage of the second option is, also depending on the
asymmetry in node capacities of each physical node, there may be
more emulated nodes allocated on a single physical node as another.
This patch implements the second option; we sacrifice the
possibility that we may have slightly more emulated nodes on a
particular physical node compared to another in lieu of node size
asymmetry.
[ Note that "node capacity" of a physical node is not only a
function of its addressable range, but also is affected by
subtracting out the amount of reserved memory over that range.
NUMA emulation only deals with available, non-reserved memory
quantities. ]
We ensure there is at least a minimal amount of available memory
allocated to each node. We also make sure that at least this
amount of available memory is available in ZONE_DMA32 for any node
that includes both ZONE_DMA32 and ZONE_NORMAL.
This patch also cleans the emulation code up by no longer passing
the statically allocated struct bootnode array among the various
functions. This init.data array is not allocated on the stack since
it may be very large and thus it may be accessed at file scope.
The WARN_ON() for nodes_cover_memory() when faking proximity
domains is removed since it relies on successive nodes always
having greater start addresses than previous nodes; with
interleaving this is no longer always true.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Ankita Garg <ankita@in.ibm.com>
Cc: Len Brown <len.brown@intel.com>
LKML-Reference: <alpine.DEB.1.00.0909251519150.14754@chino.kir.corp.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This is the counterpart to "x86: export k8 physical topology" for
SRAT. It is not as invasive because the acpi code already seperates
node setup into detection and registration steps, with the
exception of registering e820 active regions in
acpi_numa_memory_affinity_init(). This is now moved to
acpi_scan_nodes() if NUMA emulation is disabled or deferred.
acpi_numa_init() now returns a value which specifies whether an
underlying SRAT was located. If so, that topology can be used by
the emulation code to interleave emulated nodes over physical nodes
or to register the nodes for ACPI.
acpi_get_nodes() may now be used to export the srat physical
topology of the machine for NUMA emulation.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Ankita Garg <ankita@in.ibm.com>
Cc: Len Brown <len.brown@intel.com>
LKML-Reference: <alpine.DEB.1.00.0909251518580.14754@chino.kir.corp.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Need to clear both nodes and nodes_add state for start/end.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <20090718065657.GA2898@basil.fritz.box>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: stable@kernel.org
Recently there were some changes to the meaning of node_possible_map,
and it is quite strange:
- the node without memory would be set in node_possible_map
- but some node with less NODE_MIN_SIZE will be kicked out of node_possible_map.
fix it by adding strict_setup_node_bootmem().
Also, remove unparse_node().
so result will be:
1. cpu_to_node() will return online node only (nearest one)
2. apicid_to_node() still returns the node that could be not online but is set
in node_possible_map.
3. node_possible_map will include nodes that mem on it are less NODE_MIN_SIZE
v2: after move_cpus_to_node change.
[ Impact: get node_possible_map right ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Tested-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <4A0C49BE.6080800@kernel.org>
[ v3: various small cleanups and comment clarifications ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
after:
| commit b263295dbf
| Author: Christoph Lameter <clameter@sgi.com>
| Date: Wed Jan 30 13:30:47 2008 +0100
|
| x86: 64-bit, make sparsemem vmemmap the only memory model
we don't have MEMORY_HOTPLUG_RESERVE anymore.
Historically, x86-64 had an architecture-specific method for memory hotplug
whereby it scanned the SRAT for physical memory ranges that could be
potentially used for memory hot-add later. By reserving those ranges
without physical memory, the memmap would be allocated and left dormant
until needed. This depended on the DISCONTIG memory model which has been
removed so the code implementing HOTPLUG_RESERVE is now dead.
This patch removes the dead code used by MEMORY_HOTPLUG_RESERVE.
(Changelog authored by Mel.)
v2: updated changelog, and remove hotadd= in doc
[ Impact: remove dead code ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Mel Gorman <mel@csn.ul.ie>
Workflow-found-OK-by: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A0C4910.7090508@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It is expected that there might be slight differences between the e820
map and the SRAT table and the intention was that 1MB of slack be allowed.
The calculation comparing e820ram and pxmram assumes the units are bytes,
when they are in fact pages. This means 4GB of slack is being allowed,
not 1MB. This patch makes the correct comparison.
comment is from Mel.
[ Impact: don't accept buggy SRATs that could dump up to 4G of RAM ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A03E13E.6050107@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
node_cover_memory() sanity checks the SRAT table by ensuring that all
PXMs cover the memory reported in the e820.
However, when calculating the size of the holes in the e820, it uses
the early_node_map[] which contains information taken from both SRAT
and e820. If the SRAT is missing an entry, then it is not detected
that the SRAT table is incorrect and missing entries.
This patch uses the e820 map to calculate the holes instead of
early_node_map[].
comment is from Mel.
[ Impact: reject incorrect SRAT tables ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <4A03E10C.60906@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The mem= option will truncate the memory map at a specified address so
it's not possible to register nodes with memory beyond the e820 upper
bound.
unparse_node() is only called when then node had memory associated with
it, although with the mem= option it is no longer addressable.
[ Impact: fix boot hang on certain (large) systems ]
Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <alpine.DEB.2.00.0905051248150.20021@chino.kir.corp.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add support for nodes that have cpus but no memory.
The current code was failing to add these nodes
to the nodes_present_map.
v2: Fixes case caught by David Rientjes - missed support
for the x2apic SRAT table.
[ Impact: fix potential boot crash on memory-less UV nodes. ]
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20090417142242.GA23743@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
All logical processors with APIC ID values of 255 and greater will have their
APIC reported through Processor X2APIC structure (type-9 entry type) and all
logical processors with APIC ID less than 255 will have their APIC reported
through legacy Processor Local APIC (type-0 entry type) only. This is the
same case even for NMI structure reporting.
The Processor X2APIC Affinity structure provides the association between the
X2APIC ID of a logical processor and the proximity domain to which the logical
processor belongs.
For OSPM, Procssor IDs outside the 0-254 range are to be declared as Device()
objects in the ACPI namespace.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Fix:
arch/x86/mm/srat_64.c: In function ‘acpi_numa_processor_affinity_init’:
arch/x86/mm/srat_64.c:141: error: implicit declaration of function ‘get_uv_system_type’
arch/x86/mm/srat_64.c:141: error: ‘UV_X2APIC’ undeclared (first use in this function)
arch/x86/mm/srat_64.c:141: error: (Each undeclared identifier is reported only once
arch/x86/mm/srat_64.c:141: error: for each function it appears in.)
A couple of UV definitions were moved to asm/uv/uv.h, but srat_64.c did
not include that header. Add it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, futureproof
In fact, all cpumask ops will only be valid (in general) for bit
numbers < nr_cpu_ids. So use that instead of NR_CPUS in various
places.
This is always safe: no cpu number can be >= nr_cpu_ids, and
nr_cpu_ids is initialized to NR_CPUS at boot.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Portions of the ACPI code needs to know if a system is a UV system prior
to genapic initialization. This patch adds a call early_acpi_boot_init()
so that the apic type is discovered earlier.
V2 of the patch adding fixes from Yinghai Lu.
Much cleaner and smaller.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
save the SLIT, in case we are using fixmap to read it, and that fixmap
could be cleared by others.
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* Introduce a new PER_CPU macro called "EARLY_PER_CPU". This is
used by some per_cpu variables that are initialized and accessed
before there are per_cpu areas allocated.
["Early" in respect to per_cpu variables is "earlier than the per_cpu
areas have been setup".]
This patchset adds these new macros:
DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)
EXPORT_EARLY_PER_CPU_SYMBOL(_name)
DECLARE_EARLY_PER_CPU(_type, _name)
early_per_cpu_ptr(_name)
early_per_cpu_map(_name, _idx)
early_per_cpu(_name, _cpu)
The DEFINE macro defines the per_cpu variable as well as the early
map and pointer. It also initializes the per_cpu variable and map
elements to "_initvalue". The early_* macros provide access to
the initial map (usually setup during system init) and the early
pointer. This pointer is initialized to point to the early map
but is then NULL'ed when the actual per_cpu areas are setup. After
that the per_cpu variable is the correct access to the variable.
The early_per_cpu() macro is not very efficient but does show how to
access the variable if you have a function that can be called both
"early" and "late". It tests the early ptr to be NULL, and if not
then it's still valid. Otherwise, the per_cpu variable is used
instead:
#define early_per_cpu(_name, _cpu) \
(early_per_cpu_ptr(_name) ? \
early_per_cpu_ptr(_name)[_cpu] : \
per_cpu(_name, _cpu))
A better method is to actually check the pointer manually. In the
case below, numa_set_node can be called both "early" and "late":
void __cpuinit numa_set_node(int cpu, int node)
{
int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);
if (cpu_to_node_map)
cpu_to_node_map[cpu] = node;
else
per_cpu(x86_cpu_to_node_map, cpu) = node;
}
* Add a flag "arch_provides_topology_pointers" that indicates pointers
to topology cpumask_t maps are available. Otherwise, use the function
returning the cpumask_t value. This is useful if cpumask_t set size
is very large to avoid copying data on to/off of the stack.
* The coverage of CONFIG_DEBUG_PER_CPU_MAPS has been increased while
the non-debug case has been optimized a bit.
* Remove an unreferenced compiler warning in drivers/base/topology.c
* Clean up #ifdef in setup.c
For inclusion into sched-devel/latest tree.
Based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
+ sched-devel/latest .../mingo/linux-2.6-sched-devel.git
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This is a SLIT sanity checking patch. It moves slit_valid() function to
generic ACPI code and does sanity checking for both x86 and ia64. It sets up
node_distance with LOCAL_DISTANCE and REMOTE_DISTANCE when hitting invalid
SLIT table on ia64. It also cleans up unused variable localities in
acpi_parse_slit() on x86.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>
memory_add_physaddr_to_nid() is only used in the
CONFIG_MEMORY_HOTPLUG_SPARSE || CONFIG_ACPI_HOTPLUG_MEMORY case.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For example, If the physical address layout on a two node system with 8 GB
memory is something like:
node 0: 0-2GB, 4-6GB
node 1: 2-4GB, 6-8GB
Current kernels fail to boot/detect this NUMA topology.
ACPI SRAT tables can expose such a topology which needs to be supported.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Increase the number of bits in an apicid from 8 to 32.
By default, MP_processor_info() gets the APICID from the
mpc_config_processor structure. However, this structure limits
the size of APICID to 8 bits. This patch allows the caller of
MP_processor_info() to optionally pass a larger APICID that will
be used instead of the one in the mpc_config_processor struct.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
we don't need get that so early.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
reserve_hotadd() are only used by __init acpi_numa_memory_affinity_init().
Annotate reserve_hotadd() with __init is the trivial fix.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patchset adds a flags variable to reserve_bootmem() and uses the
BOOTMEM_EXCLUSIVE flag in crashkernel reservation code to detect collisions
between crashkernel area and already used memory.
This patch:
Change the reserve_bootmem() function to accept a new flag BOOTMEM_EXCLUSIVE.
If that flag is set, the function returns with -EBUSY if the memory already
has been reserved in the past. This is to avoid conflicts.
Because that code runs before SMP initialisation, there's no race condition
inside reserve_bootmem_core().
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix powerpc build]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: <linux-arch@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix the following warnings:
WARNING: arch/x86/mm/built-in.o(.text+0x1abc): Section mismatch: reference to .init.data:nodes_parsed in 'unparse_node'
WARNING: arch/x86/mm/built-in.o(.text+0x1ac6): Section mismatch: reference to .cpuinit.data:apicid_to_node in 'unparse_node'
WARNING: arch/x86/mm/built-in.o(.text+0x1ad2): Section mismatch: reference to .cpuinit.data:apicid_to_node in 'unparse_node'
unparse_node are static and only used by acpi_scan_nodes which
is already annotated __init.
So we annotate unparse_node with __init.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
I found a small bug of NUMA emulation code for x86_64. (CONFIG_NUMA_EMU)
If machine is non-NUMA, find_node_by_addr() should return
NUMA_NO_NODE, but current implementation code returns existent maximum
NUMA node number + 1.
This is not existent NUMA node number.
However, this behaviour does not affect NUMA emulation fortunately, because
acpi_fake_nodes() that is caller of find_node_by_addr() gets pxm
(proximity domain) by node_to_pxm() from non-existent NUMA node number
that was returned by find_node_by_addr().
node_to_pxm() returns PXM_INVAL that means illegal or non-existent
NUMA node number.
Signed-off-by: Minoru Usui <usui@mxm.nes.nec.co.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Change static bios_cpu_apicid array to a per_cpu data variable.
This includes using a static array used during initialization
similar to the way x86_cpu_to_apicid[] is handled.
There is one early use of bios_cpu_apicid in apic_is_clustered_box().
The other reference in cpu_present_to_apicid() is called after
smp_set_apicids() has setup the percpu version of bios_cpu_apicid.
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Change the following static arrays sized by NR_CPUS to
per_cpu data variables:
char cpu_to_node_map[NR_CPUS];
fixup:
- Split cpu_to_node function into "early" and "late" versions
so that x86_cpu_to_node_map_early_ptr is not EXPORT'ed and
the cpu_to_node inline function is more streamlined.
- This also involves setting up the percpu maps as early as possible.
- Fix X86_32 NUMA build errors that previous version of this
patch caused.
V2->V3:
- add early_cpu_to_node function to keep cpu_to_node efficient
- move and rename smp_set_apicids() to setup_percpu_maps()
- call setup_percpu_maps() as early as possible
V1->V2:
- Removed extraneous casts
- Fix !NUMA builds with '#ifdef CONFIG_NUMA"
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Change the size of node ids from 8 bits to 16 bits to
accomodate more than 256 nodes.
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Change the size of APICIDs from u8 to u16. This partially
supports the new x2apic mode that will be present on future
processor chips. (Chips actually support 32-bit APICIDs, but that
change is more intrusive. Supporting 16-bit is sufficient for now).
Signed-off-by: Jack Steiner <steiner@sgi.com>
I've included just the partial change from u8 to u16 apicids. The
remaining x2apic changes will be in a separate patch.
In addition, the fake_node_to_pxm_map[] and fake_apicid_to_node[]
tables have been moved from local data to the __initdata section
reducing stack pressure when MAX_NUMNODES and MAX_LOCAL_APIC are
increased in size.
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Use sparsemem as the only memory model for UP, SMP and NUMA. Measurements
indicate that DISCONTIGMEM has a higher overhead than sparsemem. And
FLATMEMs benefits are minimal. So I think its best to simply standardize
on sparsemem.
Results of page allocator tests (test can be had via git from slab git
tree branch tests)
Measurements in cycle counts. 1000 allocations were performed and then the
average cycle count was calculated.
Order FlatMem Discontig SparseMem
0 639 665 641
1 567 647 593
2 679 774 692
3 763 967 781
4 961 1501 962
5 1356 2344 1392
6 2224 3982 2336
7 4869 7225 5074
8 12500 14048 12732
9 27926 28223 28165
10 58578 58714 58682
(Note that FlatMem is an SMP config and the rest NUMA configurations)
Memory use:
SMP Sparsemem
-------------
Kernel size:
text data bss dec hex filename
3849268 397739 1264856 5511863 541ab7 vmlinux
total used free shared buffers cached
Mem: 8242252 41164 8201088 0 352 11512
-/+ buffers/cache: 29300 8212952
Swap: 9775512 0 9775512
SMP Flatmem
-----------
Kernel size:
text data bss dec hex filename
3844612 397739 1264536 5506887 540747 vmlinux
So 4.5k growth in text size vs. FLATMEM.
total used free shared buffers cached
Mem: 8244052 40544 8203508 0 352 11484
-/+ buffers/cache: 28708 8215344
2k growth in overall memory use after boot.
NUMA discontig:
text data bss dec hex filename
3888124 470659 1276504 5635287 55fcd7 vmlinux
total used free shared buffers cached
Mem: 8256256 56908 8199348 0 352 11496
-/+ buffers/cache: 45060 8211196
Swap: 9775512 0 9775512
NUMA sparse:
text data bss dec hex filename
3896428 470659 1276824 5643911 561e87 vmlinux
8k text growth. Given that we fully inline virt_to_page and friends now
that is rather good.
total used free shared buffers cached
Mem: 8264720 57240 8207480 0 352 11516
-/+ buffers/cache: 45372 8219348
Swap: 9775512 0 9775512
The total available memory is increased by 8k.
This patch makes sparsemem the default and removes discontig and
flatmem support from x86.
[ akpm@linux-foundation.org: allnoconfig build fix ]
Acked-by: Andi Kleen <ak@suse.de>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
In x86_64 and i386 architectures most arrays that are sized using
NR_CPUS lay in local memory on node 0. Not only will most (99%?) of the
systems not use all the slots in these arrays, particularly when NR_CPUS
is increased to accommodate future very high cpu count systems, but a
number of cache lines are passed unnecessarily on the system bus when
these arrays are referenced by cpus on other nodes.
Typically, the values in these arrays are referenced by the cpu
accessing it's own values, though when passing IPI interrupts, the cpu
does access the data relevant to the targeted cpu/node. Of course, if
the referencing cpu is not on node 0, then the reference will still
require cross node exchanges of cache lines. A common use of this is
for an interrupt service routine to pass the interrupt to other cpus
local to that node.
Ideally, all the elements in these arrays should be moved to the per_cpu
data area. In some cases (such as x86_cpu_to_apicid) the array is
referenced before the per_cpu data areas are setup. In this case, a
static array is declared in the __initdata area and initialized by the
booting cpu (BSP). The values are then moved to the per_cpu area after
it is initialized and the original static array is freed with the rest
of the __initdata.
This patch:
Fix four instances where cpu_to_node is referenced by array instead of
via the cpu_to_node macro. This is preparation to moving it to the
per_cpu data area.
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
