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ded23ac627
Fix a few trivial mistakes in Documentation/cputopology.txt Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
42 lines
1.6 KiB
Plaintext
42 lines
1.6 KiB
Plaintext
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Export cpu topology info via sysfs. Items (attributes) are similar
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to /proc/cpuinfo.
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1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
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represent the physical package id of cpu X;
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2) /sys/devices/system/cpu/cpuX/topology/core_id:
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represent the cpu core id to cpu X;
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3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
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represent the thread siblings to cpu X in the same core;
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4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
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represent the thread siblings to cpu X in the same physical package;
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To implement it in an architecture-neutral way, a new source file,
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drivers/base/topology.c, is to export the 4 attributes.
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If one architecture wants to support this feature, it just needs to
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implement 4 defines, typically in file include/asm-XXX/topology.h.
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The 4 defines are:
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#define topology_physical_package_id(cpu)
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#define topology_core_id(cpu)
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#define topology_thread_siblings(cpu)
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#define topology_core_siblings(cpu)
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The type of **_id is int.
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The type of siblings is cpumask_t.
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To be consistent on all architectures, the 4 attributes should have
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deafult values if their values are unavailable. Below is the rule.
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1) physical_package_id: If cpu has no physical package id, -1 is the
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default value.
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2) core_id: If cpu doesn't support multi-core, its core id is 0.
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3) thread_siblings: Just include itself, if the cpu doesn't support
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HT/multi-thread.
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4) core_siblings: Just include itself, if the cpu doesn't support
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multi-core and HT/Multi-thread.
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So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
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If an attribute isn't defined on an architecture, it won't be exported.
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