From owner-freebsd-arch  Wed Jan 31 12: 8: 9 2001
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To: Dan Nelson <dnelson@emsphone.com>
Cc: Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>,
	arch@FreeBSD.ORG
Subject: Re: Bumping up {MAX,DFLT}*PHYS (was Re: Bumping up {MAX,DFL}*SIZ in i386)
References: <vmhf2g5lrj.wl@rina.r.dl.itc.u-tokyo.ac.jp> <20010131140416.C21193@dan.emsphone.com>
From: Dag-Erling Smorgrav <des@ofug.org>
Date: 31 Jan 2001 21:07:45 +0100
In-Reply-To: Dan Nelson's message of "Wed, 31 Jan 2001 14:04:17 -0600"
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Dan Nelson <dnelson@emsphone.com> writes:
> On a similar note, is there any reason for us to have DFLTPHYS at 64k
> anymore?  With the insane interface speeds of SCSI and ATA devices
> nowadays, you can easily hit 600 I/Os per second on sequential reads
> (40MB/sec, 64K per I/O).  Would anything break if MAXPHYS/DFLTPHYS was
> bumped to say, 1mb?

I think so; we can't do DMA transfers larger than 64k (128k in word
mode) - at least for ISA devices, I don't know much about PCI.

DES
-- 
Dag-Erling Smorgrav - des@ofug.org


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