llvm dev - Feb 2016 - MCJit Runtine Performance

On 4 February 2016 at 22:48, Morten Brodersen via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> Hi Rafael,
>
> Not easily (llc).
>
> Is there a way to make MCJit not use the large code model when JIT'ing?
>
I think Davide started adding support for the small code model.

Cheers,
Rafael

Actually, reading over all of this again, I realize I may have made the
wrong statement. The runtime regressions we see in julia are actually
regressions in how long LLVM itself takes to do the compilation (but since
it happens at run time in the JIT case, I think of it as a regression in
our running time). We have only noticed occasional regressions in the
performance of the generated code (which we are in the process of fixing).
Which kind of regression are you talking about, time taken by LLVM or time
taken by the LLVM-generated code?

On Thu, Feb 4, 2016 at 11:44 PM, Rafael Espíndola <llvm-dev at
lists.llvm.org>
wrote:
> On 4 February 2016 at 22:48, Morten Brodersen via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > Hi Rafael,
> >
> > Not easily (llc).
> >
> > Is there a way to make MCJit not use the large code model when
JIT'ing?
> >
>
> I think Davide started adding support for the small code model.
>
> Cheers,
> Rafael
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Hi Keno,

I am talking about runtime. The performance of the generated machine 
code. Not the time it takes to lower the IR to machine code.

We typically only JIT once (taking a few secs) and then run the 
generated machine code for hours. So the JIT time (IR -> machine code) 
doesn't impact us.

Cheers
Morten

On 05/02/16 15:58, Keno Fischer wrote:
> Actually, reading over all of this again, I realize I may have made 
> the wrong statement. The runtime regressions we see in julia are 
> actually regressions in how long LLVM itself takes to do the 
> compilation (but since it happens at run time in the JIT case, I think 
> of it as a regression in our running time). We have only noticed 
> occasional regressions in the performance of the generated code (which 
> we are in the process of fixing). Which kind of regression are you 
> talking about, time taken by LLVM or time taken by the LLVM-generated 
> code?
>
> On Thu, Feb 4, 2016 at 11:44 PM, Rafael Espíndola 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>
>     On 4 February 2016 at 22:48, Morten Brodersen via llvm-dev
>     <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>     > Hi Rafael,
>     >
>     > Not easily (llc).
>     >
>     > Is there a way to make MCJit not use the large code model when
>     JIT'ing?
>     >
>
>     I think Davide started adding support for the small code model.
>
>     Cheers,
>     Rafael
>     _______________________________________________
>     LLVM Developers mailing list
>     llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>     http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
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