Date: Wed, 20 Feb 2008 11:37:28 -0500 From: "Kevin K" <kkutzko@teksavvy.com> To: "'Ivan Voras'" <ivoras@freebsd.org>, <freebsd-stable@freebsd.org> Subject: RE: Dual Core Xeon / i386 install w/ more than 4gb of RAM Message-ID: <001d01c873de$e1cef5b0$a56ce110$@com> In-Reply-To: <fphkml$m2m$1@ger.gmane.org> References: <20080220035752.GR99258@elvis.mu.org> <4594886.5961203490569242.JavaMail.root@ly.sdf.com> <fphkml$m2m$1@ger.gmane.org>
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Thank you all for your suggestions. I have been trying to push to move = to amd64 architecture for all the reasons you all stated. For the = record, we tested PAE on one machine, booted the kernel w/ nextboot and = it crashed about 15 minutes later. I will consider configuring a dump = device to analyze the kernel dumps, but for now we reverted to the = original i386 kernel and are likely going to scrap the PAE idea and move = to amd64. This was a management decision (obviously) and the people who originally = built this box (long before I was there), did not have enough experience = or foresight. i was hoping for alternative suggestions to reduce = downtime of these boxes, such as recompiling amd64 manually instead of a = fresh install. These boxes are just Apache, Mysql, PHP type boxes. Nothing exotic or = fancy. Thanks again for your suggestions. I am trying my best to relay the = reasoning and rock-solid logic ;) -----Original Message----- From: owner-freebsd-stable@freebsd.org = [mailto:owner-freebsd-stable@freebsd.org] On Behalf Of Ivan Voras Sent: Wednesday, February 20, 2008 11:35 AM To: freebsd-stable@freebsd.org Subject: Re: Dual Core Xeon / i386 install w/ more than 4gb of RAM Tom Samplonius wrote: > Is PAE really that stable? I thought it was fairly unpolished, = mainly because PAE is seen as a weak kludge implemented by Intel because = they all thought we would all be using Itanium's by now. Intel reversed = their folly pretty quickly, adopted the x86-64 extensions as-is from = AMD, and pushed them onto every piece of silicon they make. Architecturally, it's a nasty kludge. As far as stability on FreeBSD is = concerned, my only machine under PAE with 4 GB RAM (without PAE it would = use a bit over 3 GB) is very solid on 6-STABLE. > I also really don't know how anyone would properly use 16GB of RAM = under PAE anyways? Each process is going to limited to just under 4GB. = The kernel memory space can't be bigger than 4GB either, so forget about = a huge disk cache. As I understand it, one possible benefit could be to use the memory for = disk / file cache. AFAIK the pages are just pages, without distinction = where they are mapped, and for example, if you run PostgreSQL, it = couldn't use more than 4 GB for its own data (actually closer to 2 GB = because of some sysvshm issues) but it will indirectly use the cache. > And is there some really stability fear about FreeBSD on x86-64? = Seems just the same as i386. I agree, FreeBSD on amd64 is very stable.
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