Date: Sun, 29 Aug 2004 16:36:27 -0700 From: "David O'Brien" <obrien@freebsd.org> To: Sean McNeil <sean@mcneil.com> Cc: freebsd-amd64@freebsd.org Subject: Re: cvsup on amd64 just broke today Message-ID: <20040829233627.GB95117@dragon.nuxi.com> In-Reply-To: <1093820864.65009.9.camel@server.mcneil.com> References: <20040809184110.V80973@carver.gumbysoft.com> <XFMail.20040809205443.conrads@cox.net> <20040829225314.GE92947@dragon.nuxi.com> <1093820864.65009.9.camel@server.mcneil.com>
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On Sun, Aug 29, 2004 at 04:07:44PM -0700, Sean McNeil wrote: > Finally catching up on your email? ;) Yeah. :-/ > On Sun, 2004-08-29 at 15:53, David O'Brien wrote: > > Why is it odd?!? > > The ability to run legacy 32-bit x86 binaries under a 64-bit OS at > > full-speed is one of the huge capabilities AMD brought with this > > architecture. Unless a binary does 64-bit math or addresses >4GB of > > memory why does something need to be 64-bit??? > > This is a little misleading. You are throwing out the fact that the > amd64 has additional features in 64-bit mode that can significantly > increase performance. Such as extra registers. I'm not throwing out the fact about the extra registers. In my day-job I track AMD performance. Trust me, for a network-based program such as CVSup isn't going to reap a noticeable benefit from them. What slows down CVSup is network BW and latency, same for the disk BW and latency. CVSup isn't doing Seti@Home calculations. > > The fact that all Open Source OS's have a 64-bit userland on all their > > 64-bit platforms that grew up from 32-bit CPU's shows how unsophisticated > > our build framework is. "64-bit" Solaris today is really a 64-bit kernel > > and mostly 32-bit userland. > > Except Solaris has identical architectures that were extended to > 64-bit. Actually Sparc isn't 100% identical -- performance enhancements were made in 64-bit mode. They just aren't as many and to the extent as done in AMD64. > amd64 is a slightly different story. Solaris for AMD64 will also have a 32-bit userland, and its compiler will default to producing 32-bit binaries. For things like 'vi' and 'ls' 64-bit + extra registers simply doesn't matter. -- -- David (obrien@FreeBSD.org)
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