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authorLinus Torvalds <torvalds@linux-foundation.org>2009-01-03 12:04:39 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-03 12:04:39 -0800
commit7d3b56ba37a95f1f370f50258ed3954c304c524b (patch)
tree86102527b92f02450aa245f084ffb491c18d2e0a /Documentation
parent269b012321f2f1f8e4648c43a93bf432b42c6668 (diff)
parentab14398abd195af91a744c320a52a1bce814dd1e (diff)
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Merge branch 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (77 commits) x86: setup_per_cpu_areas() cleanup cpumask: fix compile error when CONFIG_NR_CPUS is not defined cpumask: use alloc_cpumask_var_node where appropriate cpumask: convert shared_cpu_map in acpi_processor* structs to cpumask_var_t x86: use cpumask_var_t in acpi/boot.c x86: cleanup some remaining usages of NR_CPUS where s/b nr_cpu_ids sched: put back some stack hog changes that were undone in kernel/sched.c x86: enable cpus display of kernel_max and offlined cpus ia64: cpumask fix for is_affinity_mask_valid() cpumask: convert RCU implementations, fix xtensa: define __fls mn10300: define __fls m32r: define __fls h8300: define __fls frv: define __fls cris: define __fls cpumask: CONFIG_DISABLE_OBSOLETE_CPUMASK_FUNCTIONS cpumask: zero extra bits in alloc_cpumask_var_node cpumask: replace for_each_cpu_mask_nr with for_each_cpu in kernel/time/ cpumask: convert mm/ ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/cputopology.txt48
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt
index bd699da24666..45932ec21cee 100644
--- a/Documentation/cputopology.txt
+++ b/Documentation/cputopology.txt
@@ -31,3 +31,51 @@ not defined by include/asm-XXX/topology.h:
2) core_id: 0
3) thread_siblings: just the given CPU
4) core_siblings: just the given CPU
+
+Additionally, cpu topology information is provided under
+/sys/devices/system/cpu and includes these files. The internal
+source for the output is in brackets ("[]").
+
+ kernel_max: the maximum cpu index allowed by the kernel configuration.
+ [NR_CPUS-1]
+
+ offline: cpus that are not online because they have been
+ HOTPLUGGED off (see cpu-hotplug.txt) or exceed the limit
+ of cpus allowed by the kernel configuration (kernel_max
+ above). [~cpu_online_mask + cpus >= NR_CPUS]
+
+ online: cpus that are online and being scheduled [cpu_online_mask]
+
+ possible: cpus that have been allocated resources and can be
+ brought online if they are present. [cpu_possible_mask]
+
+ present: cpus that have been identified as being present in the
+ system. [cpu_present_mask]
+
+The format for the above output is compatible with cpulist_parse()
+[see <linux/cpumask.h>]. Some examples follow.
+
+In this example, there are 64 cpus in the system but cpus 32-63 exceed
+the kernel max which is limited to 0..31 by the NR_CPUS config option
+being 32. Note also that cpus 2 and 4-31 are not online but could be
+brought online as they are both present and possible.
+
+ kernel_max: 31
+ offline: 2,4-31,32-63
+ online: 0-1,3
+ possible: 0-31
+ present: 0-31
+
+In this example, the NR_CPUS config option is 128, but the kernel was
+started with possible_cpus=144. There are 4 cpus in the system and cpu2
+was manually taken offline (and is the only cpu that can be brought
+online.)
+
+ kernel_max: 127
+ offline: 2,4-127,128-143
+ online: 0-1,3
+ possible: 0-127
+ present: 0-3
+
+See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter
+as well as more information on the various cpumask's.
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