diff options
author | Mike Travis <travis@sgi.com> | 2008-12-17 17:14:30 -0500 |
---|---|---|
committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-12-19 02:17:12 -0500 |
commit | d62720ade82c5e5b8f9585e5ed02c89573ebf111 (patch) | |
tree | 3453017e698d207e74768adb115b8a3071b29706 /Documentation | |
parent | e057d7aea9d8f2a46cd440d8bfb72245d4e72d79 (diff) |
sysfs: add documentation to cputopology.txt for system cpumasks
Add information to cputopology.txt explaining the output of various
system cpumask's.
Signed-off-by: Mike Travis <travis@sgi.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/cputopology.txt | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt index bd699da2466..45932ec21ce 100644 --- a/Documentation/cputopology.txt +++ b/Documentation/cputopology.txt | |||
@@ -31,3 +31,51 @@ not defined by include/asm-XXX/topology.h: | |||
31 | 2) core_id: 0 | 31 | 2) core_id: 0 |
32 | 3) thread_siblings: just the given CPU | 32 | 3) thread_siblings: just the given CPU |
33 | 4) core_siblings: just the given CPU | 33 | 4) core_siblings: just the given CPU |
34 | |||
35 | Additionally, cpu topology information is provided under | ||
36 | /sys/devices/system/cpu and includes these files. The internal | ||
37 | source for the output is in brackets ("[]"). | ||
38 | |||
39 | kernel_max: the maximum cpu index allowed by the kernel configuration. | ||
40 | [NR_CPUS-1] | ||
41 | |||
42 | offline: cpus that are not online because they have been | ||
43 | HOTPLUGGED off (see cpu-hotplug.txt) or exceed the limit | ||
44 | of cpus allowed by the kernel configuration (kernel_max | ||
45 | above). [~cpu_online_mask + cpus >= NR_CPUS] | ||
46 | |||
47 | online: cpus that are online and being scheduled [cpu_online_mask] | ||
48 | |||
49 | possible: cpus that have been allocated resources and can be | ||
50 | brought online if they are present. [cpu_possible_mask] | ||
51 | |||
52 | present: cpus that have been identified as being present in the | ||
53 | system. [cpu_present_mask] | ||
54 | |||
55 | The format for the above output is compatible with cpulist_parse() | ||
56 | [see <linux/cpumask.h>]. Some examples follow. | ||
57 | |||
58 | In this example, there are 64 cpus in the system but cpus 32-63 exceed | ||
59 | the kernel max which is limited to 0..31 by the NR_CPUS config option | ||
60 | being 32. Note also that cpus 2 and 4-31 are not online but could be | ||
61 | brought online as they are both present and possible. | ||
62 | |||
63 | kernel_max: 31 | ||
64 | offline: 2,4-31,32-63 | ||
65 | online: 0-1,3 | ||
66 | possible: 0-31 | ||
67 | present: 0-31 | ||
68 | |||
69 | In this example, the NR_CPUS config option is 128, but the kernel was | ||
70 | started with possible_cpus=144. There are 4 cpus in the system and cpu2 | ||
71 | was manually taken offline (and is the only cpu that can be brought | ||
72 | online.) | ||
73 | |||
74 | kernel_max: 127 | ||
75 | offline: 2,4-127,128-143 | ||
76 | online: 0-1,3 | ||
77 | possible: 0-127 | ||
78 | present: 0-3 | ||
79 | |||
80 | See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter | ||
81 | as well as more information on the various cpumask's. | ||