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combinations during emulation
The distance transforming in numa_emulation() used to call
numa_set_distance() for all MAX_NUMNODES * MAX_NUMNODES node
combinations regardless of which are enabled. As numa_set_distance()
ignores all out-of-bound distance settings, this doesn't cause any
problem other than looping unnecessarily many times during boot.
However, as MAX_NUMNODES * MAX_NUMNODES can be pretty high, update the
code such that it iterates through only the enabled combinations.
Yinghai Lu identified the issue and provided an initial patch to
address the issue; however, the patch was incorrect in that it didn't
build emulated distance table when there's no physical distance table
and unnecessarily complex.
http://thread.gmane.org/gmane.linux.kernel/1107986/focus=1107988
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Yinghai Lu <yinghai@kernel.org>
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Undetermined entries in emu_nid_to_phys[] are filled with zero
assuming that physical node 0 is always online; however, this might
not be true depending on hardware configuration. Find a physical node
which is actually online and use it instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: David Rientjes <rientjes@google.com>
LKML-Reference: <alpine.DEB.2.00.1103020628210.31626@chino.kir.corp.google.com>
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On one system that does not have RAM on node0.
When numa_emulation is compiled in, and
1. boot system without numa=fake...
2. or boot system with numa=fake=128 to make emulation fail
will get:
[ 0.092026] ------------[ cut here ]------------
[ 0.096005] kernel BUG at arch/x86/mm/numa_emulation.c:439!
[ 0.096005] invalid opcode: 0000 [#1] SMP
[ 0.096005] last sysfs file:
[ 0.096005] CPU 0
[ 0.096005] Modules linked in:
[ 0.096005]
[ 0.096005] Pid: 0, comm: swapper Not tainted 2.6.38-rc6-tip-yh-03869-gcb0491d-dirty #684 Sun Microsystems Sun Fire X4240/Sun Fire X4240
[ 0.096005] RIP: 0010:[<ffffffff81cdc65b>] [<ffffffff81cdc65b>] numa_add_cpu+0x56/0xcf
[ 0.096005] RSP: 0000:ffffffff82437ed8 EFLAGS: 00010246
...
[ 0.096005] Call Trace:
[ 0.096005] [<ffffffff81cd7931>] identify_cpu+0x2d7/0x2df
[ 0.096005] [<ffffffff827e54fa>] identify_boot_cpu+0x10/0x30
[ 0.096005] [<ffffffff827e5704>] check_bugs+0x9/0x2d
[ 0.096005] [<ffffffff827dceda>] start_kernel+0x3d7/0x3f1
[ 0.096005] [<ffffffff827dc2cc>] x86_64_start_reservations+0x9c/0xa0
[ 0.096005] [<ffffffff827dc4ad>] x86_64_start_kernel+0x1dd/0x1e8
[ 0.096005] Code: 74 06 48 8d 04 90 eb 0f 48 c7 c0 30 d9 00 00 48 03 04 d5 90 0f 60 82 8b 00 83 f8 ff 74 0d 0f a3 05 8b 7e 92 00 19 d2 85 d2 75 02 <0f> 0b 48 98 be 00 01 00 00 48 c7 c7 e0 44 60 82 44 8b 2c 85 e0
[ 0.096005] RIP [<ffffffff81cdc65b>] numa_add_cpu+0x56/0xcf
[ 0.096005] RSP <ffffffff82437ed8>
[ 0.096026] ---[ end trace a7919e7f17c0a725 ]---
We need to use early_cpu_to_node() directly, because numa_cpu_node()
will return node0 that is not onlined.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Handling of out-of-bounds distances and allocation failure can use
better documentation. Add it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
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NUMA distance table handling has the following problems.
* numa_reset_distance() uses numa_distance * sizeof(numa_distance[0])
as the table size when it should be using the square of
numa_distance.
* The same size miscalculation when allocation space for phys_dist in
numa_emulation().
* In numa_emulation(), phys_dist must be reserved; otherwise, the new
emulated distance table may overlap it.
Fix them and, while at it, take numa_distance_cnt resetting in
numa_reset_distance() out of the if block to simplify the code a bit.
David Rientjes reported incorrect handling of distance table during
emulation.
-tj: Edited out numa_alloc_distance() related changes which weren't
necessary and rewrote patch description.
-v2: Ingo was unhappy with 80-column limit induced linebreaks. Let
lines run over 80-column.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: David Rientjes <rientjes@google.com>
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Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
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Create numa_emulation.c and move all NUMA emulation code there. The
definitions of struct numa_memblk and numa_meminfo are moved to
numa_64.h. Also, numa_remove_memblk_from(), numa_cleanup_meminfo(),
numa_reset_distance() along with numa_emulation() are made global.
- v2: Internal declarations moved to numa_internal.h as suggested by
Yinghai.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
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