From: Nikos Chantziaras <realnc@arcor.de>
To: gentoo-user@lists.gentoo.org
Subject: [gentoo-user] Re: -march=native is *EXTREMELY* conservative
Date: Sun, 18 Dec 2011 12:45:27 +0200 [thread overview]
Message-ID: <jckg7m$cmn$1@dough.gmane.org> (raw)
In-Reply-To: <20111218103449.GA21102@waltdnes.org>
On 12/18/2011 12:34 PM, Walter Dnes wrote:
> On Sat, Dec 17, 2011 at 08:10:54PM -0500, Walter Dnes wrote
>
>> The onboard GPU was initially incapable of handling 1080i video without
>> stuttering badly and dropping frames. After explicitly changing the
>> flags and rebuilding system+world+kernel, it displays 1080p videos
>> flawlessly. That's one big "co-incidence".
>
> This was only recently installed. Is it possible that the generic x86
> code from the initial install was the problem? And that emerging
> system+world got me full optimization?
Could be. It could also be it's because of "-mfpmath=sse". That's only
used by default on 64-bit. On 32-bit, the FPU is used for floating
point operations by default, which gives better precision (80 bit vs 64
bit) but slower speed.
But then again, that sounds too much of a performance difference. So if
I had to guess, I'd say it's because of the world rebuild that made sure
everything was built with proper optimizations.
next prev parent reply other threads:[~2011-12-18 10:46 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-17 21:07 [gentoo-user] -march=native is *EXTREMELY* conservative Walter Dnes
2011-12-17 21:53 ` Dale
2011-12-17 21:58 ` [gentoo-user] " Nikos Chantziaras
2011-12-18 1:10 ` Walter Dnes
2011-12-18 10:34 ` Walter Dnes
2011-12-18 10:45 ` Nikos Chantziaras [this message]
2011-12-18 18:10 ` Andrea Conti
2011-12-19 0:05 ` [gentoo-user] A tale of computing thud and blunder Walter Dnes
2011-12-19 0:17 ` Dale
2011-12-19 5:41 ` Pandu Poluan
2011-12-19 6:15 ` Dale
2011-12-19 6:49 ` [gentoo-user] " Nikos Chantziaras
2011-12-19 7:21 ` Dale
2011-12-19 12:49 ` walt
2011-12-19 8:14 ` [gentoo-user] " Pandu Poluan
2011-12-19 16:37 ` Paul Hartman
2011-12-18 1:15 ` [gentoo-user] -march=native is *EXTREMELY* conservative Paul Hartman
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