On Mon, 16 Feb 2004 16:36:35 -0500 "Juan Tumani" <[EMAIL PROTECTED]> wrote:
> Thanks Matt for picking up on the linker problem. Patching the kernel > would, to me, be masking the real problem. > > What other "improvements" does gcc333 have over gcc295 that might > explain why it's linked products run in a half-fast mode (take twice+ > as long)? > > JT > > > >From: Matthew Dillon <[EMAIL PROTECTED]> > >To: "Juan Tumani" <[EMAIL PROTECTED]> > >CC: [EMAIL PROTECTED], [EMAIL PROTECTED] > >Subject: Re: FreeBSD 5.2 v/s FreeBSD 4.9 MFLOPS performance > >(gcc3.3.3v/sgcc2.9.5) > >Date: Mon, 16 Feb 2004 13:12:15 -0800 (PST) > > > > I'm surprised Bruce hasn't chimed in here yet. I guess he's > > tired of repeating himself. > > > > In 4.9, libcsu, which generates crt1.o (which is the start code > > for C programs which the linker links in automatically) has this > > line in > >it: > > > > andl $~0xf, %%esp # align stack to 16-byte > > boundary > > > > So anything linked with 4.9 is going to align the stack on a > > 16 byte boundary no matter WHAT the kernel does. > > > > FreeBSD-5 does not have this alignment in its crt1.o because > > GCC3 automatically aligns the stack on a per-procedure basis. > > Or at least it is supposed to. Maybe it's broke? :-) > > > > -Matt > > Quite possibly. I run the same test using the latest GCC snapshot configured as system compiler and did not see such a massive slowdown. GCC 3.3.3 wins slightly on most tests and loses only on module #2 of the flops.c program posted here. -- Alexander Kabaev _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
