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  1. 18 Oct, 2010 2 commits
    • Hitoshi Mitake's avatar
      lockdep: Add improved subclass caching · 62016250
      Hitoshi Mitake authored 
      Current lockdep_map only caches one class with subclass == 0,
and looks up hash table of classes when subclass != 0.

It seems that this has no problem because the case of
subclass != 0 is rare. But locks of struct rq are
acquired with subclass == 1 when task migration is executed.
Task migration is high frequent event, so I modified lockdep
to cache subclasses.

I measured the score of perf bench sched messaging.
This patch has slightly but certain (order of milli seconds
or 10 milli seconds) effect when lots of tasks are running.
I'll show the result in the tail of this description.

NR_LOCKDEP_CACHING_CLASSES specifies how many classes can be
cached in the instances of lockdep_map.
I discussed with Peter Zijlstra in LinuxCon Japan about
this approach and he taught me that caching every subclasses(8)
is cleary waste of memory. So number of cached classes
should be configurable.

=== Score comparison of benchmarks ===
# "min" means best score, and "max" means worst score

for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done

before: min: 0.565000, max: 0.583000, avg: 0.572500
after:  min: 0.559000, max: 0.568000, avg: 0.563300

# with more processes
for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done

before: min: 2.274000, max: 2.298000, avg: 2.286300
after:  min: 2.242000, max: 2.270000, avg: 2.259700
Signed-off-by: default avatarHitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286269311-28336-2-git-send-email-mitake@dcl.info.waseda.ac.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      62016250
    • Ingo Molnar's avatar
      Merge branch 'linus' into core/locking · f2f108eb
      Ingo Molnar authored 
      Merge reason: Update to almost-final-.36
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      f2f108eb
  3. 17 Oct, 2010 2 commits
  5. 16 Oct, 2010 4 commits
  7. 15 Oct, 2010 10 commits
  9. 14 Oct, 2010 5 commits
    • Linus Torvalds's avatar
      Linux 2.6.36-rc8 · cd07202c
      Linus Torvalds authored
      cd07202c
    • Linus Torvalds's avatar
      Un-inline the core-dump helper functions · 3aa0ce82
      Linus Torvalds authored 
      Tony Luck reports that the addition of the access_ok() check in commit
0eead9ab ("Don't dump task struct in a.out core-dumps") broke the
ia64 compile due to missing the necessary header file includes.

Rather than add yet another include (<asm/unistd.h>) to make everything
happy, just uninline the silly core dump helper functions and move the
bodies to fs/exec.c where they make a lot more sense.

dump_seek() in particular was too big to be an inline function anyway,
and none of them are in any way performance-critical.  And we really
don't need to mess up our include file headers more than they already
are.
Reported-and-tested-by: default avatarTony Luck <tony.luck@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3aa0ce82
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 · ae42d8d4
      Linus Torvalds authored 
      * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  ehea: Fix a checksum issue on the receive path
  net: allow FEC driver to use fixed PHY support
  tg3: restore rx_dropped accounting
  b44: fix carrier detection on bind
  net: clear heap allocations for privileged ethtool actions
  NET: wimax, fix use after free
  ATM: iphase, remove sleep-inside-atomic
  ATM: mpc, fix use after free
  ATM: solos-pci, remove use after free
  net/fec: carrier off initially to avoid root mount failure
  r8169: use device model DMA API
  r8169: allocate with GFP_KERNEL flag when able to sleep
      ae42d8d4
    • Linus Torvalds's avatar
      Don't dump task struct in a.out core-dumps · 0eead9ab
      Linus Torvalds authored 
      akiphie points out that a.out core-dumps have that odd task struct
dumping that was never used and was never really a good idea (it goes
back into the mists of history, probably the original core-dumping
code).  Just remove it.

Also do the access_ok() check on dump_write().  It probably doesn't
matter (since normal filesystems all seem to do it anyway), but he
points out that it's normally done by the VFS layer, so ...

[ I suspect that we should possibly do "vfs_write()" instead of
  calling ->write directly.  That also does the whole fsnotify and write
  statistics thing, which may or may not be a good idea. ]

And just to be anal, do this all for the x86-64 32-bit a.out emulation
code too, even though it's not enabled (and won't currently even
compile)
Reported-by: default avatarakiphie <akiphie@lavabit.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0eead9ab
    • Salman Qazi's avatar
      hrtimer: Preserve timer state in remove_hrtimer() · f13d4f97
      Salman Qazi authored 
      The race is described as follows:

CPU X                                 CPU Y
remove_hrtimer
// state & QUEUED == 0
timer->state = CALLBACK
unlock timer base
timer->f(n) //very long
                                  hrtimer_start
                                    lock timer base
                                    remove_hrtimer // no effect
                                    hrtimer_enqueue
                                    timer->state = CALLBACK |
                                                   QUEUED
                                    unlock timer base
                                  hrtimer_start
                                    lock timer base
                                    remove_hrtimer
                                        mode = INACTIVE
                                        // CALLBACK bit lost!
                                    switch_hrtimer_base
                                            CALLBACK bit not set:
                                                    timer->base
                                                    changes to a
                                                    different CPU.
lock this CPU's timer base

The bug was introduced with commit ca109491 (hrtimer: removing all ur
callback modes) in 2.6.29

[ tglx: Feed new state via local variable and add a comment. ]
Signed-off-by: default avatarSalman Qazi <sqazi@google.com>
Cc: akpm@linux-foundation.org
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20101012142351.8485.21823.stgit@dungbeetle.mtv.corp.google.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
      f13d4f97
  11. 13 Oct, 2010 12 commits
  13. 12 Oct, 2010 5 commits
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