From: bqt@update.uu.se (Johnny Billquist)
Subject: [pups] Progress on 2.11BSD kernel
Date: Thu, 20 Mar 2003 00:34:21 +0100 (CET) [thread overview]
Message-ID: <Pine.LNX.4.21.0303200030310.10410-100000@Tempo.Update.UU.SE> (raw)
In-Reply-To: <200303192308.h2JN8kD04865@moe.2bsd.com>
On Wed, 19 Mar 2003, Steven M. Schultz wrote:
> The buffer cache must be entirely mapped by UMRs - so if you have a
> 32KB buffer the kernel will reserve 4 UMRs on a UNIBUS system.
> Realistically a 64KB buffer cache is about the maximum a UNIBUS system
> can have because that takes 8 of the UMRs.
Are the UMRs allocated and set up statically?
(I haven't looked inside 2BSD for a while now, and can't remember much of
the internals anymore.)
> With the old (thankfully no longer in use, etc) 3Com ethernet boards
> you had to disable 4 UMRs so the system could access the memory in the
> card - that made for a very tight fit.
How many UMRs does the system use? 8 for buffer cache, you might expect
one or two DH11s, that would require a few more, ethernet takes another
few, but it seems there shouldn't be such a shortage.
What did I miss?
Johnny
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
next prev parent reply other threads:[~2003-03-19 23:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-19 23:08 Steven M. Schultz
2003-03-19 23:15 ` David Evans
2003-03-19 23:34 ` Johnny Billquist [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-03-21 18:33 Steven M. Schultz
2003-03-21 18:26 Steven M. Schultz
2003-03-19 23:52 Steven M. Schultz
2003-03-19 19:09 Steven M. Schultz
2003-03-19 19:30 ` David Evans
2003-03-19 19:06 Carl Lowenstein
2003-03-19 19:14 ` David Evans
2003-03-19 20:12 ` David C. Jenner
2003-03-19 17:51 Steven M. Schultz
2003-03-19 18:08 ` David Evans
2003-03-19 17:36 Steven M. Schultz
2003-03-19 17:46 ` David Evans
2003-03-19 18:24 ` Ian King
2003-03-19 18:59 ` David Evans
2003-03-21 18:08 ` Ian King
2003-03-19 7:44 Ian King
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