I write scientific numerical algorithms that are very data / array intensive. Having recently moved from using the JVM to the Mono CLR, was curious about the pure numerical performance against arrays. Towards this end, wrote a partial matrix class and driver around it to test performance across
Slide, not really. If mono SIMD had a more general mapping to the GPU, or
could operate on very large vectors or matrices, possibly. Linear algebra is
an easy mapping to that stuff. However, I do more complicated stuff around
timeseries, so does not really fit into linear alg stuff.
I gues
2011/11/20 Jonathan Shore
> Slide, not really. If mono SIMD had a more general mapping to the GPU, or
> could operate on very large vectors or matrices, possibly. Linear algebra
> is an easy mapping to that stuff. However, I do more complicated stuff
> around timeseries, so does not really f
Did the code I attached get filtered? I'll post the tar.gz into bugzilla and
send the link.
Below are code snippets to calculate Ordinary Least Squares, a simpler example.
I found this to be 4x slower than C++ / Java:
Here is the "safe" and "unsafe" versions of OLS which I ran on an array si
Here is a link to and entry in bugzilla with attached code. I could not send
to the list:
http://bugzilla.xamarin.com/show_bug.cgi?id=2098
On Nov 20, 2011, at 7:41 AM, Jonathan Shore wrote:
> Did the code I attached get filtered? I'll post the tar.gz into bugzilla and
> send the link.
>
> B
Hi,
I'd like to add that you may gain something on MS JIT compiler using
for (int i = 0 ; i < x.Length ; i++)
instead of
for (int i = 0 ; i < len ; i++)
This may seem counter intuitive, however that's the scenario in which
JIT eliminates array bound checking for the x array (however not for the
Thanks, Zoltan pointed out that the performance under LLVM is pretty good, so I
probably did not have LLVM enabled. Indeed I checked and found that to be the
case (my bad). As for the pattern you mention, aware that mono is able to
avoid checks in that scenario.
More often then not, though,
Hi again,
>
> It is too bad that one cannot declare a primitive expression to be
> locally const in C#.
Maybe one could get away with something like this:
public struct FinalBox
{
public FinalBox(T value)
{
this.value = value;
}
public T Va
Yes, I see what you are doing. There is no way to modify the structure.
However doesn't it still boil down to determining whether a local variable
reference is changed. So for instance:
FinalBox len =
for (int i = 0 ; i < len ; i++)
vs
var len =
for (int i = 0 ; i < len ; i++)
On Sun, 2011-11-20 at 12:33 -0500, Jonathan Shore wrote:
> Yes, I see what you are doing. There is no way to modify the structure.
> However doesn't it still boil down to determining whether a local variable
> reference is changed.
Yeah, exactly, this is rather pointless construct ;) There sho
On the other hand, maybe it could be possible to add the final-like
mechanism to Mono's compiler. Such mechanism would be beneficial if the
CLR had some notion of local readonly variables. F# uses non-mutable
variables a lot, so maybe CLR recognizes it. I am not sure what kind of
transparent denota
As far as I know the final on local variables is only a hint for the java
compiler (javac), not jit (hotspot) engine. Detection of loop invariants is
done at runtime (during code jitting) so there's really no difference
between any of the following in modern Java jits:
1) (final) int max = array.l
Yes, the modern java JIT does not need final as does the analysis. However,
it is very nice to be able to specify constness, not only to help the JIT
along, but also in terms of documenting intent. Given that C# does not have
such a construct (too bad) / const is too constrained, the next be
On Sun, 2011-11-20 at 19:39 +0100, Dawid Weiss wrote:
>
>
> As far as I know the final on local variables is only a hint for the
> java compiler (javac), not jit (hotspot) engine. Detection of loop
> invariants is done at runtime (during code jitting) so there's really
> no difference between any
On Nov 20, 2011, at 2:28 PM, Konrad M. Kruczyński wrote:
> Maybe that's the reason there is no local readonly in the C# language -
> local variables are easily trackable. As to those used in closures (as
> mentioned by Jonathan) - as far as I know, they aren't local variables
> actually but rathe
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