Date: Mon, 18 Jun 2007 14:35:59 -0400 From: Mike Meyer <mwm@mired.org> To: Jeremy Chadwick <koitsu@FreeBSD.org> Cc: freebsd-hackers@freebsd.org, Martin Turgeon <turgeon.martin@gmail.com>, freebsd-hardware@freebsd.org Subject: Re: i386 with PAE or AMD64 on PowerEdge with 4G RAM Message-ID: <18038.53391.265513.66864@bhuda.mired.org> In-Reply-To: <20070618180813.GA13003@eos.sc1.parodius.com> References: <4676BAF0.4030703@gmail.com> <20070618180813.GA13003@eos.sc1.parodius.com>
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In <20070618180813.GA13003@eos.sc1.parodius.com>, Jeremy Chadwick <koitsu@FreeBSD.org> typed: > On Mon, Jun 18, 2007 at 01:03:44PM -0400, Martin Turgeon wrote: > > I just receive 2 PowerEdge servers (a 1950 and a 860) both with 4G of RAM. I > > installed FreeBSD 6.2 Release i386 on both of them. Unfortunately, only 3,5G > > is recognized on the 860 and 3,3G on the 1950. > > dmesg on 860: > > real memory = 3757834240 (3583 MB) > > avail memory = 3678318592 (3507 MB) > > > > I am facing a difficult decision. Should I use i386 with PAE enabled in the > > kernel (I read a lot of warnings using it) or should I go with AMD64? Which > > branch should I follow? > > Based on what I've read from some of the porters and miscellaneous > others, generally-speaking there's too many issues with amd64 (in the > sense of 32-bit vs. 64-bit compatibility -- not the fault of the kernel > or otherwise) to consider it worth switching to. If you need to run 32-bit apps on amd64 FreeBSD, you're pretty much SOL at this point. You'll have to build the the infrastructure to install your apps by hand. On the other hand, 64-bit FreeBSD is fairly solid, and most of the apps I need run as well on amd64 FreeBSD as they do on i386 FreeBSD. My last major project - the ETL code for the world largest linux-based Oracle database with 7x24 availability - has been running on x86_64 linux since day 1, over two years ago. With the exclusion of oracle, it's built entirely on FOSS apps or custom code. > I personally don't run 64-bit OSes because most developers still use > 32-bit machines and don't have a way to develop/test in 64-bit > environments. I find that extremely ironic. I've spent most of the last two days trying to put together a Linux system with python 2.5 (or later) and lxml 1.2 (or later), because I need to add an oracle library to it. While both FreeBSD and darwin ports (where I do development) have all the appropriate bits except oracle, the Linux distros don't have any of them in their packaging systems. The precompiled versions of lxml available are either 64-bit Linux or 32-bit Windows. Unfortunately, I have to have the 32-bit version since the linux dev box is running on VM software that won't run 64-bit code. > That said, I'd recommend you stick with i386 + PAE, simply for > guaranteed application compatibility. If you are going to be using standard protocols to communicate over the network, then the issue isn't compatability so much as availability - the apps you need may not be available for amd64, or may not work reliably if they are. On the other hand, something that nobody ever seems to point out is that the same CPU is noticably faster running amd64 code than i386 code. Probably has something to do with the amd64 mode having twice as many registers. If performance is an issue, it might be worth your while to see if your critical applications are available for the amd64. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information.
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