Date: Mon, 17 Feb 2003 11:39:05 -0800 From: Marcel Moolenaar <marcel@xcllnt.net> To: Andrew Gallatin <gallatin@cs.duke.edu> Cc: Peter Wemm <peter@wemm.org>, "Alan L. Cox" <alc@imimic.com>, src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha machdep.c Message-ID: <20030217193905.GB593@athlon.pn.xcllnt.net> In-Reply-To: <15952.57680.522607.835422@grasshopper.cs.duke.edu> References: <3E500717.65436EAF@imimic.com> <20030217072612.577382A89E@canning.wemm.org> <15952.57680.522607.835422@grasshopper.cs.duke.edu>
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On Mon, Feb 17, 2003 at 08:19:12AM -0500, Andrew Gallatin wrote:
>
> Peter Wemm writes:
> > I believe we have bigger problems in the MI code.. we allocate the
> > vm_page_t array to cover a linear range from the lowest entry in
> > phys_avail to the highest entry address. This means that if we have
> > machines that have 2G of ram at address 0 and another 2G at the 16G mark,
> > then that means that the MI vm code allocates enough vm_page_t's in a
> > linear array to to cover 18G of physical space. Needless to say, this
>
> That's exactly my situation. The alpha I'm porting to puts up to 16GB
> of RAM per-cpu. So a 2 CPU system with nGB/cpu has a phys_avail that
> looks like: {0,nGG,16GB,(16+n)GB}. Eg, a huge (16 - n)GB hole between
> each CPU. This could eat a lot of memory on a 64-cpu box.
>
> BTW, I think I may have seen some autotuning issues with an 8GB box.
> nbufs gets set to something absurd and an apparent infinate loop is
> entered in vfs_bio.c, for example. Have you ia64 guys run with 8GB
> yet?
Not yet. We don't even get 2GB to work all the time due to sparseness :-)
And ia64 is in the same position as alpha: busdma needs to be fixed. So
we too have "collateral damage"...
--
Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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