64e6ba1259
Counters now scale orders of magnitudes better as the number of
writers to the same counter increases. Here's the results on our
current benchmark on a 6 core machine:
cores
1 6
before 1.87s 81.09s
after 0.11s 0.32s
Note how the very heavy contention gives a slowdown rather than a
speedup as the number of cores increases, but the new implementation
slows down much less than the old one and is also generally faster.
20 lines
651 B
Haskell
20 lines
651 B
Haskell
{-# LANGUAGE BangPatterns, ForeignFunctionInterface #-}
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-- | This module defines a type for mutable, integer-valued counters.
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-- Counters are non-negative, monotonically increasing values and can
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-- be used to track e.g. the number of requests served since program
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-- start. All operations on counters are thread-safe.
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module System.Remote.Counter
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(
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Counter
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, inc
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, add
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) where
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import System.Remote.Counter.Internal
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-- | Increase the counter by one.
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inc :: Counter -> IO ()
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inc counter = add counter 1
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-- | Increase the counter by the given amount.
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foreign import ccall unsafe "hs_counter_add" add :: Counter -> Int -> IO ()
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