#3331: control-monad-queue performance regression
--------------------------------------+-------------------------------------
Reporter: lpsmith | Owner:
Type: bug | Status: closed
Priority: normal | Milestone: 6.12 branch
Component: Compiler | Version: 6.10.3
Resolution: fixed | Keywords:
Difficulty: Unknown | Os: Unknown/Multiple
Testcase: | Architecture: Unknown/Multiple
Failure: Runtime performance bug |
--------------------------------------+-------------------------------------
Changes (by simonpj):
* status: new => closed
* resolution: => fixed
Comment:
Happily the HEAD is better than 6.08. Here are the 6.08 timings for
'allison':
{{{
bash-3.2$ ./Time allison 34 20 +RTS -sstderr
allison
Timings: [84,77,77,78,77,76,78,77,76,76,78,76,76,77,77,77,77,76,76,77]
Sum: 1543
Minimum: 76
Maximum: 84
Mean: 77.15
Stddev: 1.7109938632268673
7,698,631,424 bytes allocated in the heap
5,371,953,432 bytes copied during GC (scavenged)
293,760 bytes copied during GC (not scavenged)
25,944,064 bytes maximum residency (241 sample(s))
14685 collections in generation 0 ( 6.06s)
241 collections in generation 1 ( 5.46s)
74 Mb total memory in use
INIT time 0.00s ( 0.00s elapsed)
MUT time 3.92s ( 3.89s elapsed)
GC time 11.52s ( 11.64s elapsed)
EXIT time 0.00s ( 0.00s elapsed)
Total time 15.44s ( 15.53s elapsed)
%GC time 74.6% (74.9% elapsed)
Alloc rate 1,964,733,507 bytes per MUT second
Productivity 25.4% of total user, 25.2% of total elapsed
real 0m15.545s
user 0m15.437s
sys 0m0.107s
}}}
And with the HEAD:
{{{
bash-3.2$ ./Time allison 34 20 +RTS -sstderr
allison
Timings: [80,73,72,72,71,72,72,72,73,72,72,72,71,72,71,71,71,71,71,71]
Sum: 1442
Minimum: 71
Maximum: 80
Mean: 72.1
Stddev: 1.9209372712298545
7,698,487,056 bytes allocated in the heap
5,357,441,720 bytes copied during GC
25,815,200 bytes maximum residency (238 sample(s))
848,400 bytes maximum slop
74 MB total memory in use (1 MB lost due to fragmentation)
Generation 0: 14447 collections, 0 parallel, 5.50s, 5.55s elapsed
Generation 1: 238 collections, 0 parallel, 4.85s, 4.91s elapsed
INIT time 0.00s ( 0.00s elapsed)
MUT time 4.07s ( 4.06s elapsed)
GC time 10.36s ( 10.47s elapsed)
EXIT time 0.00s ( 0.00s elapsed)
Total time 14.42s ( 14.53s elapsed)
%GC time 71.8% (72.0% elapsed)
Alloc rate 1,891,795,331 bytes per MUT second
Productivity 28.2% of total user, 28.0% of total elapsed
real 0m14.550s
user 0m14.426s
sys 0m0.121s
}}}
Notice that allocation is essentially unchanged, but elapsed time seems a
bit better. I don't know why.
When I tried this initially with HEAD I got:
{{{
bash-3.2$ time ./Time allison 34 20 +RTS -sstderr
./Time allison 34 20 +RTS -sstderr
allison
Timings: [79,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]
Sum: 79
Minimum: 0
Maximum: 79
Mean: 3.95
Stddev: 17.21765082698566
385,451,912 bytes allocated in the heap
267,303,984 bytes copied during GC
24,657,920 bytes maximum residency (13 sample(s))
805,320 bytes maximum slop
73 MB total memory in use (1 MB lost due to fragmentation)
Generation 0: 723 collections, 0 parallel, 0.28s, 0.28s elapsed
Generation 1: 13 collections, 0 parallel, 0.24s, 0.31s elapsed
INIT time 0.00s ( 0.00s elapsed)
MUT time 0.21s ( 0.21s elapsed)
GC time 0.52s ( 0.59s elapsed)
EXIT time 0.00s ( 0.00s elapsed)
Total time 0.73s ( 0.80s elapsed)
%GC time 71.4% (73.5% elapsed)
Alloc rate 1,853,428,245 bytes per MUT second
Productivity 28.5% of total user, 25.9% of total elapsed
real 0m0.818s
user 0m0.726s
sys 0m0.088s
}}}
So the HEAD is better at some kind of inlining or fusion or full laziness:
it's combining all the test runs into one! So to get the fair comparision
I had to change Time.hs. The two changes are:
{{{
test' string f i n = do
ts <- mapM (test string . f) [(k,i) | k <- [1..n]]
... blah...
}}}
and
{{{
fromQueue f (_,n) = length (f (T.fib n)) == fib n - 1
fromUnit f (_,n) = (f (T.fib n)) == ()
}}}
That is, the test functions take a parameter they don't use. Otherwise
full laziness makes `test'` too efficient. '''You may want to make this
change in the package itself'''.
I have not tried with GHC 6.12, because even if it's slower, I doubt we'll
go back to fix it.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3331#comment:5>
GHC <http://www.haskell.org/ghc/>
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