[lld] r232460 - [ELF] Use parallel_for_each for writing.

[Rafael Espíndola]

On 18 March 2015 at 12:14, Shankar Easwaran <shankare at codeaurora.org> wrote:
> Does this repeat with the same numbers across similar tries ?

The "-r 20" tells perf to do 20 runs. Repeating the entire thing for
sanity check I got


master:
       1850.315854      task-clock (msec)         #    0.999 CPUs
utilized            ( +-  0.20% )
             1,246      context-switches          #    0.673 K/sec
                 0      cpu-migrations            #    0.000 K/sec
               ( +-100.00% )
           191,223      page-faults               #    0.103 M/sec
               ( +-  0.00% )
     5,570,279,746      cycles                    #    3.010 GHz
               ( +-  0.08% )
     3,076,652,220      stalled-cycles-frontend   #   55.23% frontend
cycles idle     ( +-  0.15% )
   <not supported>      stalled-cycles-backend
     6,061,467,442      instructions              #    1.09  insns per
cycle
                                                  #    0.51  stalled
cycles per insn  ( +-  0.00% )
     1,262,014,047      branches                  #  682.053 M/sec
               ( +-  0.00% )
        26,526,169      branch-misses             #    2.10% of all
branches          ( +-  0.00% )

       1.852094924 seconds time elapsed
          ( +-  0.20% )

master minus your patch:

       1837.986418      task-clock (msec)         #    0.999 CPUs
utilized            ( +-  0.01% )
             1,170      context-switches          #    0.637 K/sec
                 0      cpu-migrations            #    0.000 K/sec
           191,225      page-faults               #    0.104 M/sec
               ( +-  0.00% )
     5,517,484,340      cycles                    #    3.002 GHz
               ( +-  0.01% )
     3,036,583,530      stalled-cycles-frontend   #   55.04% frontend
cycles idle     ( +-  0.02% )
   <not supported>      stalled-cycles-backend
     6,004,436,870      instructions              #    1.09  insns per
cycle
                                                  #    0.51  stalled
cycles per insn  ( +-  0.00% )
     1,250,685,716      branches                  #  680.465 M/sec
               ( +-  0.00% )
        26,539,486      branch-misses             #    2.12% of all
branches          ( +-  0.00% )

       1.839759787 seconds time elapsed
          ( +-  0.01% )


Cheers,
Rafael