Skip to content

L
linux
Switch branch/tag
  1. 23 May, 2008 3 commits
    • Mike Travis's avatar
      x86: Add performance variants of cpumask operators · 41df0d61
      Mike Travis authored 
        * Increase performance for systems with large count NR_CPUS by limiting
    the range of the cpumask operators that loop over the bits in a cpumask_t
    variable.  This removes a large amount of wasted cpu cycles.

  * Add performance variants of the cpumask operators:

    int cpus_weight_nr(mask)	     Same using nr_cpu_ids instead of NR_CPUS
    int first_cpu_nr(mask)	     Number lowest set bit, or nr_cpu_ids
    int next_cpu_nr(cpu, mask)	     Next cpu past 'cpu', or nr_cpu_ids
    for_each_cpu_mask_nr(cpu, mask)  for-loop cpu over mask using nr_cpu_ids

  * Modify following to use performance variants:

    #define num_online_cpus()	cpus_weight_nr(cpu_online_map)
    #define num_possible_cpus()	cpus_weight_nr(cpu_possible_map)
    #define num_present_cpus()	cpus_weight_nr(cpu_present_map)

    #define for_each_possible_cpu(cpu) for_each_cpu_mask_nr((cpu), ...)
    #define for_each_online_cpu(cpu)   for_each_cpu_mask_nr((cpu), ...)
    #define for_each_present_cpu(cpu)  for_each_cpu_mask_nr((cpu), ...)

  * Comment added to include/linux/cpumask.h:

    Note: The alternate operations with the suffix "_nr" are used
	  to limit the range of the loop to nr_cpu_ids instead of
	  NR_CPUS when NR_CPUS > 64 for performance reasons.
	  If NR_CPUS is <= 64 then most assembler bitmask
	  operators execute faster with a constant range, so
	  the operator will continue to use NR_CPUS.

	  Another consideration is that nr_cpu_ids is initialized
	  to NR_CPUS and isn't lowered until the possible cpus are
	  discovered (including any disabled cpus).  So early uses
	  will span the entire range of NR_CPUS.

    (The net effect is that for systems with 64 or less CPU's there are no
     functional changes.)

For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git

Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Reviewed-by: default avatarPaul Jackson <pj@sgi.com>
Reviewed-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarMike Travis <travis@sgi.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      41df0d61
    • Mike Travis's avatar
      cpu: change some globals to statics in drivers/base/cpu.c v2 · 143aa5c5
      Mike Travis authored 
      This patch makes the following needlessly global code static:
- attr_online_map
- attr_possible_map
- attr_present_map

- cpu_state_attr [v2]
Signed-off-by: default avatarAdrian Bunk <bunk@kernel.org>
Signed-off-by: default avatarMike Travis <travis@sgi.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      143aa5c5
    • Mike Travis's avatar
      sched: replace MAX_NUMNODES with nr_node_ids in kernel/sched.c · a953e459
      Mike Travis authored 
        * Replace usages of MAX_NUMNODES with nr_node_ids in kernel/sched.c,
    where appropriate.  This saves some allocated space as well as many
    wasted cycles going through node entries that are non-existent.

For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git
Signed-off-by: default avatarMike Travis <travis@sgi.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      a953e459
  3. 22 May, 2008 14 commits
  5. 21 May, 2008 23 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7