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Re^2: Inline::C on Windows: how to improve performance of compiled code?

by vr (Curate)
on Jun 15, 2018 at 06:43 UTC ( #1216697=note: print w/replies, xml ) Need Help??


in reply to Re: Inline::C on Windows: how to improve performance of compiled code?
in thread Inline::C on Windows: how to improve performance of compiled code?

# 18.2613549232483 # 3.09944152832031e-006 # 7.17122101783752 # 0.186490774154663

Those are results of running your example (with 1e8 iterations) on Windows and Linux, respectively. Looks to me, "C from C" on Windows got optimized away, but "C from Perl" gives same picture (lagging behind, W vs L) as in OP. And right now I'm interested in eliminating this lagging. Optimization to try to avoid 1e8 calls is in future plans ;).

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Re^3: Inline::C on Windows: how to improve performance of compiled code?
by syphilis (Archbishop) on Jun 15, 2018 at 09:02 UTC
    Looks to me, "C from C" on Windows got optimized away

    I don't think so. (Could be wrong but.)
    A clearer ilustration is (hopefully) this script:
    use Time::HiRes qw(time); use Inline C => Config => #OPTIMIZE => '-O0', FORCE_BUILD => 1; use Inline C => <<'EOC'; void foo() {} void foo_bar(int x) { int i; for(i = 0; i < x; i++){ foo(); } } EOC $iterations = 10000000; $t = time; foo() for 1 .. $iterations; print "# ", time - $t, "\n"; $t = time; foo_bar($iterations); print "# ", time - $t, "\n";
    As it stands, with optimization enabled, it outputs (on Windows):
    # 1.02960205078125 # 1.00135803222656e-005
    Now that second value does look like something was optimized away. I'm thinking the loop is simply doing nothing at each iteration.
    When we switch optimization off by including the "OPTIMIZE => '-O0'" line, the output changes to (on Windows):
    # 1.10760188102722 # 0.0196361541748047
    The "C from C" code now takes 500 times longer to execute - because, I think, this time foo() is actually being called at each iteration. But it's still 50 times quicker than calling "C from Perl".

    I've no useful ideas regarding things that can be done to enable Windows to access C subs as quickly as it can access Perl subs - and that's the main reason that I'm avoiding that aspect.

    Cheers,
    Rob

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