From owner-freebsd-questions Tue Jan 30 12:46:01 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id MAA27748 for questions-outgoing; Tue, 30 Jan 1996 12:46:01 -0800 (PST) Received: from Sysiphos (Sysiphos.MI.Uni-Koeln.DE [134.95.212.10]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id MAA27743 for ; Tue, 30 Jan 1996 12:45:52 -0800 (PST) Received: by Sysiphos id AA04431 (5.67b/IDA-1.5 for questions@freebsd.org); Tue, 30 Jan 1996 21:45:40 +0100 Message-Id: <199601302045.AA04431@Sysiphos> From: se@zpr.uni-koeln.de (Stefan Esser) Date: Tue, 30 Jan 1996 21:45:39 +0100 In-Reply-To: Eric Chet "Re: various questions" (Jan 30, 15:26) X-Mailer: Mail User's Shell (7.2.6 alpha(2) 7/9/95) To: Eric Chet Subject: Re: various questions Cc: questions@freebsd.org Sender: owner-questions@freebsd.org Precedence: bulk On Jan 30, 15:26, Eric Chet wrote: } Subject: Re: various questions } } > The Dirty Tag RAM and write-back cache mode ought to make } > more of a difference on a DX4 system. But I doubt you'll } > see more than some 5% to 7% speedup. } } Thanks Stefan } } I was looking at the wrong numbers. Are there any problems } using a Intel DX4(which has write-back L1) on a SP3G with write-back } L2 cache? The SP3G is said to have problems, with write-back L1 && L2. The Saturn technical data book contains a section on supported cache configurations, and explicitly states, that ONLY ONE of the caches can operate in write-back mode. This is a design limititation. In fact it seems like a primary cache is not suypported at all. I.e. it can't be used with the Pentium Overdrive nor any other CPU, AFAIK. (I.e. I never heard of anybody using a i486DX4 with WB primary cache in a motherboard with Saturn chip set). I suppose a write-back primary cache had more effect on effective throughput than a WB secondary cache, but the Saturn was faster with both caches set to write-through than most other 486 chip sets with WB support, anyway. Regards, STefan -- Stefan Esser, Zentrum fuer Paralleles Rechnen Tel: +49 221 4706021 Universitaet zu Koeln, Weyertal 80, 50931 Koeln FAX: +49 221 4705160 ============================================================================== http://www.zpr.uni-koeln.de/~se