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

[Shankar Easwaran]

It looks like these are the right numbers and Strange, I dont see a huge 
advantage of the patch trying to parallelize writing output sections in 
parallel.

On 3/18/2015 11:23 AM, Rafael Espíndola wrote:
> 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
>


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