Subject: Re: improving ssh performance on sun4m systems
To: None <port-sparc@netbsd.org>
From: Valeriy E. Ushakov <uwe@ptc.spbu.ru>
List: port-sparc
Date: 03/15/2002 20:43:56
On Fri, Mar 15, 2002 at 12:10:25 -0500, Charles Shannon Hendrix wrote:
> > : In any case, the library extension you mention will not speed up the code
> > : outside of the libraries.
> >
> > Huh!? Having an overlay listed in ld.so.conf will affect *all* code
> > (program or library) using the (shared) libc, without recompiling.
>
> All you have done here is reaffirm what I said above: this change
> affects code *in libraries*, not outside of them.
You don't understand. See page 236 of Sparc V8 manual. Without -mv8
all code is generated to call (e.g.) ".umul" function from a shared
library (libc) to perform multiplication (for v8 an "umul" instruction
would be generated). So with the overlay *all* dynamically linked
programs will call v8'ified ".umul" that just calls real "umul"
instruction, instead of doing a bunch of "mulscc".
IOW, on a real v8 the code compiled without -mv8 but being run with
the overlay will be something like:
...
call .umul
...
!! this comes from the overlay
.umul:
retl
umul ...
instead of just
umul ...
that -mv8 would generate.
SY, Uwe
--
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