An attempt on Linux failed clearing the file cache. Thus an update and results from a Linux box.

This works: sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
[download]

Results:

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time wc lesms10_big.txt 
 14152200 113528600 652751200 lesms10_big.txt

real 0m3.412s
user 0m3.307s
sys  0m0.097s

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m0.613s  (5.57x)
user 0m4.168s
sys  0m0.432s
[download]

Beyond 8 cores:

The --max-workers option defaults to auto (8 workers max). Running with --max-workers=N beyond 8 may provide extra performance on a box with more than 8 "real" cores.

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl --max-workers=8 lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m0.613s  (5.57x)
user 0m4.168s
sys  0m0.432s

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl --max-workers=12 lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m0.454s  (7.52x)
user 0m4.464s
sys  0m0.536s

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl --max-workers=16 lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m0.360s  (9.48x)
user 0m4.344s
sys  0m0.625s
[download]

Compare wc with wc.pl 1 and 2 cores:

To complete the demonstration, I also tried wc.pl with --maxworkers=1 and --maxworkers=2. The timings for wc.pl include loading Perl plus modules and spawning/reaping workers.

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time wc lesms10_big.txt 
 14152200 113528600 652751200 lesms10_big.txt

real 0m3.412s
user 0m3.307s
sys  0m0.097s

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl --max-workers=1 lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m3.553s
user 0m3.363s
sys  0m0.329s

$ sudo bash -c "echo 1 >/proc/sys/vm/drop_caches"
$ time ./wc.pl --max-workers=2 lesms10_big.txt
 14152200 113528600 652751200 lesms10_big.txt

real 0m1.804s
user 0m3.339s
sys  0m0.357s
[download]

See also, egrep.pl from mce-examples.

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