Date: Wed, 30 Jan 2008 08:49:57 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Richard Todd <rmtodd@ichotolot.servalan.com> Subject: Re: Weird performance behaviour in 7.0 Message-ID: <200801300849.58321.jhb@freebsd.org> In-Reply-To: <x7y7a8i4qc.fsf@ichotolot.servalan.com> References: <18328.45282.562906.708945@celery.zuhause.org> <18332.52845.956601.870334@celery.zuhause.org> <x7y7a8i4qc.fsf@ichotolot.servalan.com>
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On Tuesday 29 January 2008 06:36:43 pm Richard Todd wrote: > bruce@zuhause.mn.org writes: > > > I'm curious, though, should I be worried about the memcontrol list > > entries that are listed as "set-by-firmware active bogus"? > > > > 0x0/0xf080000000 BIOS write-back set-by-firmware active bogus > > 0x80000000/0xf040000000 BIOS write-back set-by-firmware active bogus > > 0xc0000000/0xf010000000 BIOS write-back set-by-firmware active bogus > > 0xcf800000/0xf000800000 BIOS uncacheable set-by-firmware active bogus > > 0xcf700000/0xf000100000 BIOS uncacheable set-by-firmware active bogus > > 0x100000000/0xf020000000 BIOS write-back set-by-firmware active bogus > > 0x120000000/0xf008000000 BIOS write-back set-by-firmware active bogus > > Worried that it says "bogus"? No, not really. This is, as I said earlier, > the result of an issue in the amd64 machdep.c code for handling MTRRs -- > it was written for the original amd64 where the "size" field of the MTRR > was a certain width. On Core 2 Duo these fields are 4 bits shorter, so > the machdep.c code looks at 4 more bits from that register than it should and > so all the size fields have that leading "f" digit. This causes the sizes > to no longer be a power of two, which causes machdep.c to set the "bogus" > flag because those entries look funny. The "bogus" flag being set doesn't > seem to actually break anything, and as near as I can figure if you change > the memcontrol entries the correct data gets written back to the registers > even on Core2Duo, so the "bogus" warnings seem to be pretty harmless. Ahh, I will look at fixing this. -- John Baldwin
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