• Stefani Seibold's avatar
    procfs: provide stack information for threads · d899bf7b
    Stefani Seibold authored
    A patch to give a better overview of the userland application stack usage,
    especially for embedded linux.
    
    Currently you are only able to dump the main process/thread stack usage
    which is showed in /proc/pid/status by the "VmStk" Value.  But you get no
    information about the consumed stack memory of the the threads.
    
    There is an enhancement in the /proc/<pid>/{task/*,}/*maps and which marks
    the vm mapping where the thread stack pointer reside with "[thread stack
    xxxxxxxx]".  xxxxxxxx is the maximum size of stack.  This is a value
    information, because libpthread doesn't set the start of the stack to the
    top of the mapped area, depending of the pthread usage.
    
    A sample output of /proc/<pid>/task/<tid>/maps looks like:
    
    08048000-08049000 r-xp 00000000 03:00 8312       /opt/z
    08049000-0804a000 rw-p 00001000 03:00 8312       /opt/z
    0804a000-0806b000 rw-p 00000000 00:00 0          [heap]
    a7d12000-a7d13000 ---p 00000000 00:00 0
    a7d13000-a7f13000 rw-p 00000000 00:00 0          [thread stack: 001ff4b4]
    a7f13000-a7f14000 ---p 00000000 00:00 0
    a7f14000-a7f36000 rw-p 00000000 00:00 0
    a7f36000-a8069000 r-xp 00000000 03:00 4222       /lib/libc.so.6
    a8069000-a806b000 r--p 00133000 03:00 4222       /lib/libc.so.6
    a806b000-a806c000 rw-p 00135000 03:00 4222       /lib/libc.so.6
    a806c000-a806f000 rw-p 00000000 00:00 0
    a806f000-a8083000 r-xp 00000000 03:00 14462      /lib/libpthread.so.0
    a8083000-a8084000 r--p 00013000 03:00 14462      /lib/libpthread.so.0
    a8084000-a8085000 rw-p 00014000 03:00 14462      /lib/libpthread.so.0
    a8085000-a8088000 rw-p 00000000 00:00 0
    a8088000-a80a4000 r-xp 00000000 03:00 8317       /lib/ld-linux.so.2
    a80a4000-a80a5000 r--p 0001b000 03:00 8317       /lib/ld-linux.so.2
    a80a5000-a80a6000 rw-p 0001c000 03:00 8317       /lib/ld-linux.so.2
    afaf5000-afb0a000 rw-p 00000000 00:00 0          [stack]
    ffffe000-fffff000 r-xp 00000000 00:00 0          [vdso]
    
    Also there is a new entry "stack usage" in /proc/<pid>/{task/*,}/status
    which will you give the current stack usage in kb.
    
    A sample output of /proc/self/status looks like:
    
    Name:	cat
    State:	R (running)
    Tgid:	507
    Pid:	507
    .
    .
    .
    CapBnd:	fffffffffffffeff
    voluntary_ctxt_switches:	0
    nonvoluntary_ctxt_switches:	0
    Stack usage:	12 kB
    
    I also fixed stack base address in /proc/<pid>/{task/*,}/stat to the base
    address of the associated thread stack and not the one of the main
    process.  This makes more sense.
    
    [akpm@linux-foundation.org: fs/proc/array.c now needs walk_page_range()]
    Signed-off-by: default avatarStefani Seibold <stefani@seibold.net>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Alexey Dobriyan <adobriyan@gmail.com>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Cc: Randy Dunlap <randy.dunlap@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d899bf7b
task_mmu.c 20 KB