• Jesper Dangaard Brouer's avatar
    slub: fix spelling succedd to succeed · 2ae44005
    Jesper Dangaard Brouer authored
    With this patchset the SLUB allocator now has both bulk alloc and free
    implemented.
    
    This patchset mostly optimizes the "fastpath" where objects are available
    on the per CPU fastpath page.  This mostly amortize the less-heavy
    none-locked cmpxchg_double used on fastpath.
    
    The "fallback" bulking (e.g __kmem_cache_free_bulk) provides a good basis
    for comparison.  Measurements[1] of the fallback functions
    __kmem_cache_{free,alloc}_bulk have been copied from slab_common.c and
    forced "noinline" to force a function call like slab_common.c.
    
    Measurements on CPU CPU i7-4790K @ 4.00GHz
    Baseline normal fastpath (alloc+free cost): 42 cycles(tsc) 10.601 ns
    
    Measurements last-patch with disabled debugging:
    
    Bulk- fallback                   - this-patch
      1 -  57 cycles(tsc) 14.448 ns  -  44 cycles(tsc) 11.236 ns  improved 22.8%
      2 -  51 cycles(tsc) 12.768 ns  -  28 cycles(tsc)  7.019 ns  improved 45.1%
      3 -  48 cycles(tsc) 12.232 ns  -  22 cycles(tsc)  5.526 ns  improved 54.2%
      4 -  48 cycles(tsc) 12.025 ns  -  19 cycles(tsc)  4.786 ns  improved 60.4%
      8 -  46 cycles(tsc) 11.558 ns  -  18 cycles(tsc)  4.572 ns  improved 60.9%
     16 -  45 cycles(tsc) 11.458 ns  -  18 cycles(tsc)  4.658 ns  improved 60.0%
     30 -  45 cycles(tsc) 11.499 ns  -  18 cycles(tsc)  4.568 ns  improved 60.0%
     32 -  79 cycles(tsc) 19.917 ns  -  65 cycles(tsc) 16.454 ns  improved 17.7%
     34 -  78 cycles(tsc) 19.655 ns  -  63 cycles(tsc) 15.932 ns  improved 19.2%
     48 -  68 cycles(tsc) 17.049 ns  -  50 cycles(tsc) 12.506 ns  improved 26.5%
     64 -  80 cycles(tsc) 20.009 ns  -  63 cycles(tsc) 15.929 ns  improved 21.3%
    128 -  94 cycles(tsc) 23.749 ns  -  86 cycles(tsc) 21.583 ns  improved  8.5%
    158 -  97 cycles(tsc) 24.299 ns  -  90 cycles(tsc) 22.552 ns  improved  7.2%
    250 - 102 cycles(tsc) 25.681 ns  -  98 cycles(tsc) 24.589 ns  improved  3.9%
    
    Benchmarking shows impressive improvements in the "fastpath" with a small
    number of objects in the working set.  Once the working set increases,
    resulting in activating the "slowpath" (that contains the heavier locked
    cmpxchg_double) the improvement decreases.
    
    I'm currently working on also optimizing the "slowpath" (as network stack
    use-case hits this), but this patchset should provide a good foundation
    for further improvements.  Rest of my patch queue in this area needs some
    more work, but preliminary results are good.  I'm attending Netfilter
    Workshop[2] next week, and I'll hopefully return working on further
    improvements in this area.
    
    This patch (of 6):
    
    s/succedd/succeed/
    Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    2ae44005
slub.c 127 KB