• Zhang, Yanmin's avatar
    [PATCH] Export cpu topology in sysfs · 69dcc991
    Zhang, Yanmin authored
    The patch implements cpu topology exportation by sysfs.
    
    Items (attributes) are similar to /proc/cpuinfo.
    
    1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
    	represent the physical package id of  cpu X;
    2) /sys/devices/system/cpu/cpuX/topology/core_id:
    	represent the cpu core id to cpu X;
    3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
    	represent the thread siblings to cpu X in the same core;
    4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
    	represent the thread siblings to cpu X in the same physical package;
    
    To implement it in an architecture-neutral way, a new source file,
    driver/base/topology.c, is to export the 5 attributes.
    
    If one architecture wants to support this feature, it just needs to
    implement 4 defines, typically in file include/asm-XXX/topology.h.
    The 4 defines are:
    #define topology_physical_package_id(cpu)
    #define topology_core_id(cpu)
    #define topology_thread_siblings(cpu)
    #define topology_core_siblings(cpu)
    
    The type of **_id is int.
    The type of siblings is cpumask_t.
    
    To be consistent on all architectures, the 4 attributes should have
    deafult values if their values are unavailable. Below is the rule.
    
    1) physical_package_id: If cpu has no physical package id, -1 is the
    default value.
    
    2) core_id: If cpu doesn't support multi-core, its core id is 0.
    
    3) thread_siblings: Just include itself, if the cpu doesn't support
    HT/multi-thread.
    
    4) core_siblings: Just include itself, if the cpu doesn't support
    multi-core and HT/Multi-thread.
    
    So be careful when declaring the 4 defines in include/asm-XXX/topology.h.
    
    If an attribute isn't defined on an architecture, it won't be exported.
    
    Thank Nathan, Greg, Andi, Paul and Venki.
    
    The patch provides defines for i386/x86_64/ia64.
    Signed-off-by: default avatarZhang, Yanmin <yanmin.zhang@intel.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Nick Piggin <nickpiggin@yahoo.com.au>
    Cc: Greg KH <greg@kroah.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    69dcc991
topology.c 3.74 KB