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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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