1. 25 5月, 2011 1 次提交
  2. 19 5月, 2011 21 次提交
  3. 18 5月, 2011 1 次提交
  4. 14 5月, 2011 1 次提交
  5. 11 5月, 2011 5 次提交
  6. 06 4月, 2011 1 次提交
  7. 05 4月, 2011 1 次提交
    • J
      jump label: Introduce static_branch() interface · d430d3d7
      Jason Baron 提交于
      Introduce:
      
      static __always_inline bool static_branch(struct jump_label_key *key);
      
      instead of the old JUMP_LABEL(key, label) macro.
      
      In this way, jump labels become really easy to use:
      
      Define:
      
              struct jump_label_key jump_key;
      
      Can be used as:
      
              if (static_branch(&jump_key))
                      do unlikely code
      
      enable/disale via:
      
              jump_label_inc(&jump_key);
              jump_label_dec(&jump_key);
      
      that's it!
      
      For the jump labels disabled case, the static_branch() becomes an
      atomic_read(), and jump_label_inc()/dec() are simply atomic_inc(),
      atomic_dec() operations. We show testing results for this change below.
      
      Thanks to H. Peter Anvin for suggesting the 'static_branch()' construct.
      
      Since we now require a 'struct jump_label_key *key', we can store a pointer into
      the jump table addresses. In this way, we can enable/disable jump labels, in
      basically constant time. This change allows us to completely remove the previous
      hashtable scheme. Thanks to Peter Zijlstra for this re-write.
      
      Testing:
      
      I ran a series of 'tbench 20' runs 5 times (with reboots) for 3
      configurations, where tracepoints were disabled.
      
      jump label configured in
      avg: 815.6
      
      jump label *not* configured in (using atomic reads)
      avg: 800.1
      
      jump label *not* configured in (regular reads)
      avg: 803.4
      Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
      LKML-Reference: <20110316212947.GA8792@redhat.com>
      Signed-off-by: NJason Baron <jbaron@redhat.com>
      Suggested-by: NH. Peter Anvin <hpa@linux.intel.com>
      Tested-by: NDavid Daney <ddaney@caviumnetworks.com>
      Acked-by: NRalf Baechle <ralf@linux-mips.org>
      Acked-by: NDavid S. Miller <davem@davemloft.net>
      Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
      Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      d430d3d7
  8. 31 3月, 2011 1 次提交
  9. 29 3月, 2011 2 次提交
  10. 26 3月, 2011 6 次提交