Re: [Haskell-cafe] blas bindings, why are they so much slower the C?
so I had a look at the code. The loops are all fine. replicateM_ isn't
a problem, but getDot is decidedly non trivial. Lots of pattern matching
on different vector forms, and to top it off ffi calls.
With some inlining in the blas library I was able to cut a few seconds
off the running time, but getDot looks to be fundamentally a bit
complicated in the current implementation.
I wonder if you'll get different results with hmatrix?
Anyway, this is a library issue. Better take it up with Patrick.
Pass on to the library author the C code, the Haskell you think should
be compiled identically.
-- Don
aeyakovenko:
i get the same crappy performance with:
$ cat htestdot.hs
{-# OPTIONS_GHC -O2 -fexcess-precision -funbox-strict-fields
-fglasgow-exts -fbang-patterns -lcblas#-}
module Main where
import Data.Vector.Dense.IO
import Control.Monad
main = do
let size = 10
let times = 10*1000*1000
v1::IOVector Int Double - newListVector size $ replicate size 0.1
v2::IOVector Int Double - newListVector size $ replicate size 0.1
replicateM_ times $ v1 `getDot` v2
On Fri, Jun 27, 2008 at 7:41 PM, Dan Doel [EMAIL PROTECTED] wrote:
On Friday 27 June 2008, Anatoly Yakovenko wrote:
$ cat htestdot.hs
{-# OPTIONS_GHC -O2 -fexcess-precision -funbox-strict-fields
-fglasgow-exts -fbang-patterns -lcblas#-}
module Main where
import Data.Vector.Dense.IO
import Control.Monad
main = do
let size = 10
let times = 10*1000*1000
v1::IOVector Int Double - newListVector size $ replicate size 0.1
v2::IOVector Int Double - newListVector size $ replicate size 0.1
sum - foldM (\ ii zz - do
rv - v1 `getDot` v2
return $ zz + rv
) 0.0 [0..times]
print $ sum
Hackage is down for the time being, so I can't install blas and look at the
core for your program. However, there are still some reasons why this code
would be slow.
For instance, a brief experiment seems to indicate that foldM is not a good
consumer in the foldr/build sense, so no deforestation occurs. Your program
is iterating over a 10-million element lazy list. That's going to add
overhead. I wrote a simple test program which just adds 0.1 in each
iteration:
snip
{-# LANGUAGE BangPatterns #-}
module Main (main) where
import Control.Monad
main = do
let times = 10*1000*1000
sum - foldM (\_ zz - return $ zz + 0.1) 0.0 [0..times]
-- sum - foo 0 times 0.0
print $ sum
foo :: Int - Int - Double - IO Double
foo k m !zz
| k = m = foo (k+1) m (zz + 0.1)
| otherwise = return zz
snip
With foldM, it takes 2.5 seconds on my machine. If you comment that line,
and
use foo instead, it takes around .1 seconds. So that's a factor of what,
250?
That loop allows for a lot more unboxing, which allows much better code to
be
generated.
When Hackage comes back online, I'll take a look at your code, and see if I
can make it run faster, but you might want to try it yourself in the time
being. Strictifying the addition of the accumulator is probably a good idea,
for instance.
Cheers,
-- Dan
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Sat Jun 28 00:33:17 PDT 2008 Don Stewart [EMAIL PROTECTED]
* Some inlining and unpacking for DVectors
New patches:
[Some inlining and unpacking for DVectors
Don Stewart [EMAIL PROTECTED]**20080628073317] {
hunk ./BLAS/Internal.hs 115
+{-# INLINE checkVecVecOp #-}
hunk ./Data/Vector/Dense/Internal.hs 78
-data DVector t n e =
- DV { fptr :: !(ForeignPtr e) -- ^ a pointer to the storage region
- , offset :: !Int-- ^ an offset (in elements, not bytes)
to the first element in the vector.
- , len:: !Int-- ^ the length of the vector
- , stride :: !Int-- ^ the stride (in elements, not bytes)
between elements.
+data DVector t n e =
+ DV { fptr :: {-# UNPACK #-} !(ForeignPtr e) -- ^ a pointer to the
storage region
+ , offset :: {-# UNPACK #-} !Int-- ^ an offset (in
elements, not bytes) to the first element in the vector.
+ , len:: {-# UNPACK #-} !Int-- ^ the length of the
vector
+ , stride :: {-# UNPACK #-} !Int-- ^ the stride (in
elements, not bytes) between elements.
hunk ./Data/Vector/Dense/Internal.hs 84
-| C !(DVector t n e)-- ^ a conjugated vector
+| C {-# UNPACK #-} !(DVector t n e)-- ^ a conjugated vector
hunk ./Data/Vector/Dense/Internal.hs 92
+{-# INLINE coerceVector #-}
hunk ./Data/Vector/Dense/Internal.hs 424
+
hunk ./Data/Vector/Dense/Operations.hs 144
+{-# INLINE getDot #-}
hunk ./Data/Vector/Dense/Operations.hs 153
-unsafeGetDot x@(DV _ _ _ _) (C (C y)) =
+unsafeGetDot x@(DV _ _ _ _) (C (C y)) =
hunk ./Data/Vector/Dense/Operations.hs 155
Re: [Haskell-cafe] Re: Haskell on ARM (was Re: ANN: Topkata)
Hello Jeremy, Jeremy Apthorp wrote: Next year I'll be working on a project for my undergraduate computing course at UNSW that will involve getting GHC to target the Nintendo DS. It'll require cross-compilation, because the DS isn't powerful enough to actually run GHC (4M main ram and a 66MHz processor). It'll also require that I significantly strip down the runtime system, as the current RTS won't fit in 4M and leave any left over for the main application. Maybe one of these would help (running Linux) .. http://www.iyonix.com/ It'd be good too have a native code generator support for ARM (not via C). Many years ago I tinkered with implementing a lazy FPL on ARM (on my Acorn Risc PC). I never even started the compiler but got a basic single threaded RTS and mark-sweep-compact garbage collector up and running (written in ARM assembler). It wasn't really useable for real programs though as I had to write my function definitions as comments and actually implement the graph reduction code by hand in assembler :-) But I remember the ARM instruction set had some really useful features that made things like checking for stack-heap collision cheap and if you got the register allocation right (which is not hard on the ARM) you could construct the overwhelming majority of heap records using a single STMIA instruction. Almost seemed like it's instruction set was designed for efficient FPL implementation :-) Regards -- Adrian Hey ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] The ping method in HDBC
Hi, there I'm wondering if there's a ping method in HDBC that does the same thing as Perl DBI's ping. Please see the following link for details: http://search.cpan.org/~timb/DBI-1.605/DBI.pm#ping I think It's rather important for database auto-connection when preserving database connections for a quite long time in fastcgi applications. Any ideas? Thanks in advance! -agentzh ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Haskell Related Reading
I have a trip coming up and might have some reading time. I was hoping to get through some of the classics, bananas and lenses, the essence, etc. So I have a few questions: Bananas and lenses et. al. uses some notation that I don't understand right out of the gate. Is there a good primer on whatever that brand of double bars and arrows means? The essense of functional programming looks good, I could understand it when I skimmed it but can I print it out on US letter? The PDF at citeseer was aligned badly. (Essece seemed like a fabulous intro or chapter 2 on getting used to monads. Better than most stuff on the web. Funny that...) I'm also interested in FRP as it might relate to web programming. Anyone have a recommendation? -- Darrin ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Hackage
Hi, Hackage seems to have been down for a few days now. When is it going to be back online? It is not possible to darcs-get any packages either. Best Regards, Cetin Sert ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Galois move complete, Hackage back online
Galois has completed the move of its data center, and the services: hackage.haskell.org darcs.haskell.org are now back online. Thanks for your patience, everyone! Enjoy the new bandwidth. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Learning GADT types to simulate dependent types
I'm trying to understand how to use GADT types to simulate dependent
types. I'm trying to write a version of list that uses Peano numbers
in the types to keep track of how many elements are in the list. Like this:
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
module Plist where
infixr 3 :|
data Zero
data S a
class Add n1 n2 t | n1 n2 - t, n1 t - n2
instance Add Zero n n
instance Add (S n1) n2 (S t)
data Plist n a where
Nil :: Plist Zero a
(:|) :: a - Plist n a - Plist (S n) a
instance (Show a) = Show (Plist n a) where
show Nil = Nil
show (x :| xs) = show x ++ :| ++ show xs
pHead :: Plist (S n) a - a
pHead (x :| _) = x
pTail :: Plist (S n) a - Plist n a
pTail (_ :| xs) = xs
pConcat Nil ys = ys
pConcat (x :| xs) ys = x :| pConcat xs ys
Everything works except the last function (pConcat). I figured that it
should add the lengths of its arguments together, so I created a class
Add as shown in the Haskell Wiki at
http://www.haskell.org/haskellwiki/Type_arithmetic. But now I'm stuck.
When I try to load this module I get:
Plist.hs:32:8:
GADT pattern match in non-rigid context for `Nil'
Tell GHC HQ if you'd like this to unify the context
In the pattern: Nil
In the definition of `pConcat': pConcat Nil ys = ys
Failed, modules loaded: none.
(Line 32 is pConcat Nil ys = ys)
So how do I do this? Am I on the right track? Can someone help improve
my Oleg rating?
Thanks,
Paul.
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Re: [Haskell-cafe] Learning GADT types to simulate dependent types
Am Samstag, 28. Juni 2008 19:51 schrieb Paul Johnson:
I'm trying to understand how to use GADT types to simulate dependent
types. I'm trying to write a version of list that uses Peano numbers
in the types to keep track of how many elements are in the list. Like
this:
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
module Plist where
infixr 3 :|
data Zero
data S a
class Add n1 n2 t | n1 n2 - t, n1 t - n2
instance Add Zero n n
instance Add (S n1) n2 (S t)
data Plist n a where
Nil :: Plist Zero a
(:|) :: a - Plist n a - Plist (S n) a
instance (Show a) = Show (Plist n a) where
show Nil = Nil
show (x :| xs) = show x ++ :| ++ show xs
pHead :: Plist (S n) a - a
pHead (x :| _) = x
pTail :: Plist (S n) a - Plist n a
pTail (_ :| xs) = xs
pConcat Nil ys = ys
pConcat (x :| xs) ys = x :| pConcat xs ys
Everything works except the last function (pConcat). I figured that it
should add the lengths of its arguments together, so I created a class
Add as shown in the Haskell Wiki at
http://www.haskell.org/haskellwiki/Type_arithmetic. But now I'm stuck.
When I try to load this module I get:
Plist.hs:32:8:
GADT pattern match in non-rigid context for `Nil'
Tell GHC HQ if you'd like this to unify the context
In the pattern: Nil
In the definition of `pConcat': pConcat Nil ys = ys
Failed, modules loaded: none.
(Line 32 is pConcat Nil ys = ys)
So how do I do this? Am I on the right track? Can someone help improve
my Oleg rating?
Thanks,
Paul.
My Oleg rating isn't high either, and certainly you can do it more elegant,
but
class Concat l1 l2 l3 | l1 l2 - l3, l1 l3 - l2 where
pConcat :: l1 a - l2 a - l3 a
instance Concat (Plist Zero) (Plist n) (Plist n) where
pConcat _ ys = ys
instance Concat (Plist n1) (Plist n2) (Plist t) =
Concat (Plist (S n1)) (Plist n2) (Plist (S t)) where
pConcat (x :| xs) ys = x :| pConcat xs ys
works, you don't even need the Add class then - btw, you'd want
instance Add n1 n2 t = Add (S n1) n2 (S t)
anyway.
Cheers,
Daniel
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Re: [Haskell-cafe] Learning GADT types to simulate dependent types
On Saturday 28 June 2008, Paul Johnson wrote:
I'm trying to understand how to use GADT types to simulate dependent
types. I'm trying to write a version of list that uses Peano numbers
in the types to keep track of how many elements are in the list. Like
this:
{-# OPTIONS -fglasgow-exts -fallow-undecidable-instances #-}
module Plist where
infixr 3 :|
data Zero
data S a
class Add n1 n2 t | n1 n2 - t, n1 t - n2
instance Add Zero n n
instance Add (S n1) n2 (S t)
data Plist n a where
Nil :: Plist Zero a
(:|) :: a - Plist n a - Plist (S n) a
instance (Show a) = Show (Plist n a) where
show Nil = Nil
show (x :| xs) = show x ++ :| ++ show xs
pHead :: Plist (S n) a - a
pHead (x :| _) = x
pTail :: Plist (S n) a - Plist n a
pTail (_ :| xs) = xs
pConcat Nil ys = ys
pConcat (x :| xs) ys = x :| pConcat xs ys
Everything works except the last function (pConcat). I figured that it
should add the lengths of its arguments together, so I created a class
Add as shown in the Haskell Wiki at
http://www.haskell.org/haskellwiki/Type_arithmetic. But now I'm stuck.
When I try to load this module I get:
Plist.hs:32:8:
GADT pattern match in non-rigid context for `Nil'
Tell GHC HQ if you'd like this to unify the context
In the pattern: Nil
In the definition of `pConcat': pConcat Nil ys = ys
Failed, modules loaded: none.
(Line 32 is pConcat Nil ys = ys)
So how do I do this? Am I on the right track? Can someone help improve
my Oleg rating?
There are a couple issues that jump out at me. First, your second instance for
Add is a bit off. It should be more like:
instance (Add n1 n2 t) = Add (S n1) n2 (S t)
Second, the reason you're getting that particular error with pConcat is that
it doesn't have a type signature. Matching on GADTs requires one. However,
fixing those here, I still got errors, and I'm not enough of a type
class/fundep wizard to know what the problem is. Instead, I might suggest
using type families for the type-level arithmetic:
type family Add n1 n2 :: *
type instance Add Zero n2 = n2
type instance Add (S n1) n2 = S (Add n1 n2)
Then the signature of pConcat becomes:
pConcat :: Plist m a - Plist n a - Plist (Add m n) a
Which works fine. As an added bonus, the type family doesn't require
undecidable instances like the type class does.
Type families are a bit iffy in 6.8.*, but they'll work all right for simple
stuff like this, at least.
Cheers,
-- Dan
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Re: [Haskell-cafe] Learning GADT types to simulate dependent types
Daniel Fischer wrote: My Oleg rating isn't high either, and certainly you can do it more elegant, but class Concat l1 l2 l3 | l1 l2 - l3, l1 l3 - l2 where pConcat :: l1 a - l2 a - l3 a instance Concat (Plist Zero) (Plist n) (Plist n) where pConcat _ ys = ys instance Concat (Plist n1) (Plist n2) (Plist t) = Concat (Plist (S n1)) (Plist n2) (Plist (S t)) where pConcat (x :| xs) ys = x :| pConcat xs ys works, you don't even need the Add class then - btw, you'd want instance Add n1 n2 t = Add (S n1) n2 (S t) anyway. Thanks, and also thanks to Dan Doel who showed how to do it with the new type families. I'll stick with the Fundeps solution here for the moment until type families settle down, but that method is cleaner. I was also able to write this: class Concat p1 p2 p3 | p1 p2 - p3, p1 p3 - p2 where pConcat :: p1 a - p2 a - p3 a pBogus :: p1 a - p2 a - p3 a instance Concat (Plist Zero) (Plist n) (Plist n) where pConcat _ ys = ys pBogus _ ys = ys instance Concat (Plist n1) (Plist n2) (Plist t) = Concat (Plist (S n1)) (Plist n2) (Plist (S t)) where pConcat (x :| xs) ys = x :| pConcat xs ys pBogus xs ys = ys And indeed the second definition of pBogus gave me a compile-time type error because the length of the result didn't agree with the type length. I'm going to be doing a presentation on Haskell for my boss soon, and this should definitely impress (he has a solid coding background). Thanks again, Paul. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Haskell on ARM (was Re: [Haskell-cafe] ANN: Topkata)
Just a random note. jhc works fine on ARM, Another semi-random note: nhc12 and nhc13 (precursors to nhc98) were originally developed on an ARM with 2Mb of memory, way back in 1994-5. Regards, Malcolm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Ptr Word8 display question
Hi, Suppose I have a value of type Ptr Word8 and also an Int which is the length of the Ptr Word8(sorry if I am thinking too much in a C string frame of mind). How can I display the Ptr Word8 value of the given length? Vasili ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ptr Word8 display question
2008/6/28 Galchin, Vasili [EMAIL PROTECTED]: Hi, Suppose I have a value of type Ptr Word8 and also an Int which is the length of the Ptr Word8(sorry if I am thinking too much in a C string frame of mind). How can I display the Ptr Word8 value of the given length? Vasili You're best bet would be to use 'peekArray' or 'withArrayLen' to get a list of Word8 values, and then display that however you want. withArrayLen: http://haskell.org/ghc/docs/latest/html/libraries/base/Foreign-Marshal-Array.html#v%3AwithArrayLen peekArray: http://haskell.org/ghc/docs/latest/html/libraries/base/Foreign-Marshal-Array.html#v%3ApeekArray I hope that helps! -Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Ptr Word8 display question
2008/6/28 Galchin, Vasili [EMAIL PROTECTED]: Hi, Suppose I have a value of type Ptr Word8 and also an Int which is the length of the Ptr Word8(sorry if I am thinking too much in a C string frame of mind). How can I display the Ptr Word8 value of the given length? You mentioned C style strings - if you need to interface with foreign libraries which are expecting/providing actual C strings, you may also want to look at the Foreign.C.String module: http://haskell.org/ghc/docs/latest/html/libraries/base/Foreign-C-String.html -Antoine ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
