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From: Terry Lambert <terry@lambert.org>
Message-Id: <199605161712.KAA17376@phaeton.artisoft.com>
Subject: Re: EDO & Memory latency
To: dyson@freebsd.org
Date: Thu, 16 May 1996 10:12:33 -0700 (MST)
Cc: babkin@hq.icb.chel.su, hackers@freebsd.org
In-Reply-To: <199605160613.BAA07537@dyson.iquest.net> from "John S. Dyson" at May 16, 96 01:13:11 am
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> There are several things going on.  One is that there is propagation
> time through to the main memory, it is much worse than the memory cycle
> time.  Of course, that does not account for all of the 400 nsecs that you
> are seeing.

Only about 280uS.  The other 120uS are 20uS for the kernel trap and
another 100uS in unrelated overhead.

> You likely are seeing TLB overhead intrinsic to the processor.  Some
> processors don't have microcode TLB management, and you'll see worse
> numbers, because the TLB needs to be handled in normal machine/assembly
> code.  (Of course, on those processors, you can tune the TLB management
> more freely.)

Some non-Intel procesors, like the Alpha and PPC, he means.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.