[PATCH -tip 0/2] kernel/smp: Small csd_lock optimizations

[Davidlohr Bueso]

From: Davidlohr Bueso <dave@xxxxxxxxxxxx>

Hi,

Justifications are in each patch, there is slight impact (patch 2)
on some tlb flushing intensive benchmarks (albeit using ipi batching
nowadays).  Specifically for the pft
benchmark, on a 12-core box:

pft faults
                              4.4                         4.4
                          vanilla                         smp
Hmean    faults/cpu-1   801432.1608 (  0.00%)  795719.8859 ( -0.71%)
Hmean    faults/cpu-3   702578.6659 (  0.00%)  752796.6960 (  7.15%)
Hmean    faults/cpu-5   606080.3473 (  0.00%)  595890.0451 ( -1.68%)
Hmean    faults/cpu-7   460369.0724 (  0.00%)  485283.6343 (  5.41%)
Hmean    faults/cpu-12  294445.4701 (  0.00%)  298300.6011 (  1.31%)
Hmean    faults/cpu-18  213156.0860 (  0.00%)  213584.2741 (  0.20%)
Hmean    faults/cpu-24  153104.2995 (  0.00%)  153198.8473 (  0.06%)
Hmean    faults/sec-1   796329.3184 (  0.00%)  614222.4594 (-22.87%)
Hmean    faults/sec-3  1947806.7372 (  0.00%) 2169267.1582 ( 11.37%)
Hmean    faults/sec-5  2611152.0422 (  0.00%) 2544652.6871 ( -2.55%)
Hmean    faults/sec-7  2493705.4668 (  0.00%) 2674847.5270 (  7.26%)
Hmean    faults/sec-12 2583139.7724 (  0.00%) 2614404.6002 (  1.21%)
Hmean    faults/sec-18 2661410.8170 (  0.00%) 2683427.0703 (  0.83%)
Hmean    faults/sec-24 2670463.4814 (  0.00%) 2666221.6332 ( -0.16%)
Stddev   faults/cpu-1    27537.6676 (  0.00%)   25753.4945 (  6.48%)
Stddev   faults/cpu-3    62616.8041 (  0.00%)   44728.0990 ( 28.57%)
Stddev   faults/cpu-5    70976.9184 (  0.00%)   74720.5716 ( -5.27%)
Stddev   faults/cpu-7    47426.5952 (  0.00%)   32758.2705 ( 30.93%)
Stddev   faults/cpu-12    6951.8792 (  0.00%)    9097.0782 (-30.86%)
Stddev   faults/cpu-18    4293.1696 (  0.00%)    5826.9446 (-35.73%)
Stddev   faults/cpu-24    3195.0939 (  0.00%)    3373.7230 ( -5.59%)
Stddev   faults/sec-1    27315.3093 (  0.00%)  148601.7795 (-444.02%)
Stddev   faults/sec-3   271560.5941 (  0.00%)  193681.0177 ( 28.68%)
Stddev   faults/sec-5   429633.7378 (  0.00%)  458426.3306 ( -6.70%)
Stddev   faults/sec-7   338229.0746 (  0.00%)  226146.3450 ( 33.14%)
Stddev   faults/sec-12   57766.4604 (  0.00%)   82734.3638 (-43.22%)
Stddev   faults/sec-18  118572.1909 (  0.00%)  134966.7210 (-13.83%)
Stddev   faults/sec-24   57452.7350 (  0.00%)   57542.7755 ( -0.16%)

                 4.4         4.4
             vanilla         smp
User           11.91       11.85
System        197.11      194.69
Elapsed        44.24       40.26

While the single thread is an abnormality, overall we don't seem
to do any harm (noise range). Could be give or take, but overall
the patches at least make some sense afaict.

Thanks!

Davidlohr Bueso (2):
  kernel/smp: Explicitly inline cds_lock helpers
  kernel/smp: Use make csd_lock_wait be smp_cond_acquire

 kernel/smp.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--
2.1.4