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Re: Sjlj vs dwarf2 on mingw for octave
From: |
Tatsuro MATSUOKA |
Subject: |
Re: Sjlj vs dwarf2 on mingw for octave |
Date: |
Tue, 31 Mar 2009 08:21:08 +0900 (JST) |
Hello Bejamin
--- Benjamin Lindner wrote:
> Tatsuro MATSUOKA wrote:
> > The speed of binaries built with dw2 is 25 to 30 % faster than that of sjlj.
> >
> > This is a just record so that I would not like to say dw2 EH is better than
> > sjlj EH.
>
> I'd go a step further and say, yes, regarding speed dw2 IS better than
> sjlj. (It should be so by design.) dw2 is not flawless yet on windows,
> but its speed bonus is not to be neglected.
> sjlj EH also slows down dynamic memory allocation using new/delete,
> since this also involves exceptions.
> This is also the reason cygwin builds with gcc-3.3.3 were considerably
> slower than builds with gcc-3.2 or (I guess) with new gcc-4 (where dw2
> should be available again IIRC)
Thank you for your reply.
Regarding for speed of octave interpreter on mingw, the 25-30% speed up is not
negligible.
In cygwin case, the slowness of sjlj is Incredibly large. The speed of
sjlj-octave interpreter is
about three to seven times slower than that of dw2. This is not tolerable.
Thus when I distributed
octave binaries on cygwin I built the octave binaries by specially configured
gcc-3.4.4 with dw2 EH
built myself.
However, as you mentioned, dw2 is not flawless yet on windows.
This might be a reason why multithreaded ATLAS can be used only on sjlj EH.
The power of multithreaded atlas by pthread-win32 may be very large for large
matrix calculations for
multicore cpu like Core2Duo and so on. The loss of 25-30% speed down in oxtave
interpereter may be
trade-off. I think that at present the selection of either, sjlj or dw2,
relies on users' purpose at
present.
I hope that dw2-EH will be flawless in the near future and multithreaded altlas
will be able to be
used on octave built by GCC with dw2 EH.
Regards
Tatsuro
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