An update on my math-centered tests. The first is the built-in
`magnitude' vs. a TR near-transliteration of its C implementation,
called from *untyped* Racket. The numbers are in milliseconds, for 5
million calls, by input type:
Function Flonum Rational Fixnum Integer Float-Complex
-------------------------------------------------------------------
Pre-static contracts:
magnitude* 385 419 378 414 686
magnitude 59 44 40 40 390
Post-static contracts:
magnitude* 175 196 164 195 475
magnitude 68 43 36 40 406
All but the Float-Complex case just return the absolute value of the
argument, so there's not much computation. They're dominated by contract
checking, and the speedup is 0.45 to 0.5. Nice. The Float-Complex case
does something substantive, and is close to C. That's awesome.
So for really small functions (i.e. just a test and a call to `abs'),
writing them in C is still better. But for anything much larger (that
part of `magnitude*' is about 10 lines and 7-13 numeric ops), a TR
implementation isn't much slower than C (about 17%).
--
1 million iterations of some math library flonum functions, in TR,
untyped before Robby's changes, untyped after Robby's 12/12 changes, and
untyped after Eric's static contract changes, in milliseconds:
Function TR Untyped Robby's Robby's+Eric's
--------------------------------------------------------------
flrational? 5 322 98 37
flsinh 55 343 121 86
fllog1p 47 351 117 80
lg+ 61 384 154 115
flgamma 165 521 262 234
So calling TR floating-point functions from untyped Racket takes only
0.11 to 0.45 times the amount of time it took only a month ago, with
typical cases being about 0.25. That's awesome.
Neil ⊥
On 01/14/2014 10:27 AM, Eric Dobson wrote:
The changes to TR contract generation are now in at HEAD.
If you can find any cases where contracts are still slowing programs
down by a lot I'd like to take a look at them. (Excepting the case of
structs where I know it is still an issue).
On Thu, Dec 12, 2013 at 10:52 AM, Robby Findler
<ro...@eecs.northwestern.edu> wrote:
Re-reading your message I see that you're not actually asserting something
different from what I said, but just for some precision here I wish to point
out that I wasn't basing my opinion on intuition from the code, but on some
microbenchmark timings. (There was a much more substantial difference
yesterday because the loop inside any-wrap/c wasn't as cheap as it could
have been.)
I'd be interested to see if your improvements to type->contract improve the
situation any! I expect they will make things better again for the Number
case, but at the moment, there isn't a big difference.
Program 1:
#lang racket/base
(module m typed/racket/base
(: f (Any -> Any))
(define (f x) 1)
(provide f))
(require 'm)
(time
(for ([x (in-range 20000)])
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)))
Timings:
cpu time: 142 real time: 142 gc time: 8
cpu time: 144 real time: 144 gc time: 7
cpu time: 144 real time: 143 gc time: 6
cpu time: 142 real time: 142 gc time: 6
cpu time: 142 real time: 142 gc time: 7
cpu time: 146 real time: 146 gc time: 6
Program 2:
#lang racket/base
(module m typed/racket/base
(: f (Any -> Integer))
(define (f x) 1)
(provide f))
(require 'm)
(time
(for ([x (in-range 20000)])
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)
(f 0) (f 1) (f 2) (f 3) (f 4) (f 5) (f 6) (f 7)))
Timings:
cpu time: 139 real time: 138 gc time: 7
cpu time: 145 real time: 144 gc time: 7
cpu time: 140 real time: 140 gc time: 6
cpu time: 151 real time: 150 gc time: 6
cpu time: 139 real time: 138 gc time: 6
cpu time: 139 real time: 139 gc time: 8
On Thu, Dec 12, 2013 at 12:33 PM, Eric Dobson <eric.n.dob...@gmail.com>
wrote:
any-wrap/c still requires the check for one value, while any (which is
from Number not Any) does not. So I would still guess at Number being
faster, but Robby's changes may make it so that inlining and dead code
elimination can see through everything and turn it into the same code.
On Thu, Dec 12, 2013 at 10:27 AM, Robby Findler
<ro...@eecs.northwestern.edu> wrote:
FWIW, my push speeds up the any-wrap/c implementation a bunch. Those two
should have similar speeds after you get that, I guess.
Robby
On Thu, Dec 12, 2013 at 11:03 AM, Neil Toronto <neil.toro...@gmail.com>
wrote:
I tried your branch that implements it and saw about 3.5x speedup for
the
`magnitude*' test. This is of course without Robby's recent first-order
contract changes.
(I think it's about 3.5x: I tried with magnitude* : Number -> Any first
and got 2400ms on the easy tests. I changed it to magnitude* : Number
->
Number and got 690ms. Apparently, for an `Any' return type, an
`any-wrap/c'
contract is generated instead of nothing. If that's much faster to
check
than `number?', though, the speedup is even better.)
I'd love to see this with Robby's recent changes. Hint? Nudge? Please?
I didn't see very much speedup with arrays (about 1.2x). Speed tests on
the math library's distribution objects were very interesting, though,
and
indicate why the arrays might not be much faster. Here's my test
program:
#lang racket
(require math/distributions)
(define d (normal-dist 0 1))
(printf "pdf d 0~n")
(for ([_ (in-range 5)])
(time (for ([_ (in-range 100000)])
(pdf d 0))))
(newline)
(define p (distribution-pdf d))
(printf "p 0~n")
(for ([_ (in-range 5)])
(time (for ([_ (in-range 100000)])
(p 0))))
(newline)
The two tests are equivalent, as `pdf' just pulls the pdf function out
of
the distribution struct and applies it. In TR, the tests are exactly
the
same speed (extremely fast). In untyped Racket, on the main branch, the
second test is 16x faster, and on your branch, it's 44x faster. (It's
still
10x slower than TR on your branch, so again... I'd love to see your
changes
and Robby's together. :D)
Neil ⊥
On 12/12/2013 12:40 AM, Eric Dobson wrote:
Removing the return value checking is in the works. It actually is
removing all of the checks that would blame typed code, so higher
order functions/datastructure get improvements too. It is actually
functional the last time I checked, but lacking documentation which is
what is holding up merging with mainline.
https://github.com/plt/racket/pull/453
On Wed, Dec 11, 2013 at 7:57 PM, Robby Findler
<ro...@eecs.northwestern.edu> wrote:
I see that TR's type->contract returns
(-> (flat-named-contract (quote Float) flonum?)
(flat-named-contract
(quote
Float) flonum?))
for the type (Float -> Float), but it could return
(-> (flat-named-contract (quote Float) flonum?) any)
which wouldn't do any result value checking (this being different
from
any/c
as the range of the arrow contract).
Robby
On Wed, Dec 11, 2013 at 6:18 PM, Neil Toronto
<neil.toro...@gmail.com>
wrote:
On 12/11/2013 02:49 PM, Neil Toronto wrote:
On 12/11/2013 01:55 PM, Stephen Bloch wrote:
On Dec 11, 2013, at 2:36 PM, Neil Toronto wrote:
numeric primitives implemented in Typed Racket are faster than
the
same primitives implemented in C.
Whoa! How did that happen?
Whoa! That's not what I meant! O_o
I said "we might be getting close" to that. I haven't tried porting
a
numeric C primitive to TR yet, but I have a hunch that it'll still
be
slower. I'll try one now and report what I find.
Neil ⊥
I can't figure out why `flsinh' is faster to call from untyped
Racket
than
`sinh'. All my tests with a Typed Racket `magnitude' show calls from
untyped
code are significantly slower, except in the one case that it
computes
Euclidean distance. That case is only twice as slow.
I've attached the benchmark program. The `magnitude*' function is
more
or
less a direct translation of `magnitude' from "number.c" into Typed
Racket.
Here's a summary of the results I get on my computer, in
milliseconds,
for 5
million calls from untyped Racket, by data type.
Function Flonum Rational Fixnum Integer Float-Complex
-------------------------------------------------------------------
magnitude* 385 419 378 414 686
magnitude 59 44 40 40 390
The only one that's close in relative terms is Float-Complex. The
others
just call `abs'. The decompiled code doesn't show any inlining of
`magnitude', so this comparison should be good.
I'll bet checking the return value contract (which is unnecessary)
is
the
main slowdown. It has to check for number of values.
For comparison, here are the timings for running the benchmarks in
TR
with
#:no-optimize:
Function Flonum Rational Fixnum Integer Float-Complex
-------------------------------------------------------------------
magnitude* 45 70* 37 102* 318
magnitude 61 45 39 91* 394
* = unexpectedly high
Here's what I understand from comparing the numbers:
* Except for non-fixnum integers, calling `magnitude' in TR is
just
as
fast as in untyped Racket. I have no idea why it would be slower on
big
integers. That's just weird.
* Calling `abs' in Racket is faster than calling `scheme_abs' in
C,
except on rationals and big integers.
* Operating on flonums in Typed Racket, using generic numeric
functions,
is faster than doing the same in C.
Overall, it looks like the TR code is within the same order of
magnitude
(pun not intended) as the C code. I would love to try this benchmark
with
either 1) a `magnitude*' with an `AnyValues' return type; or 2) a
contract
boundary that doesn't check TR's return types for first-order
functions.
(I managed to make a `magnitude*' with type Number -> AnyValues, but
TR
couldn't make a contract for it.)
Neil ⊥
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