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Article #21650Re: DMA on RISC-based systems
From: Hugh LaMaster
Date: Thu, 08 Jun 1989 16:18
Date: Thu, 08 Jun 1989 16:18
24 lines
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1586 bytes
In article <1213@ttds.UUCP> jonasn@ttds.UUCP (Jonas Nygren) writes: >In article <8479@june.cs.washington.edu> rik@june.cs.washington.edu (Rik Littlefield) writes: >>In article <185@dg.dg.com>, rec@dg.dg.com (Robert Cousins) writes: >>< Given that a disk channel will be averaging 200K bytes/second ... >I have performed a small test on a DECstation3100 with a RZ55-230 Mb disk. >Write 15x2 Mb: 113 s, 265 kb/s >Read 15x2 Mb: 117 s, 256 kb/s >Read 15x2 + write 15x2 Mb (new and in parallell): 281 s, 213 kb/s >Mean value: 234 kb/s I have performed some single user tests. 200KBytes/sec reading rate is typical for small workstations with SCSI or similar disks, etc. With SMD on one of the newer controllers you can do ~600 KBytes/sec. On mainframes, I have seen single applications which *averaged* 3 MB/sec on 4.5 MB/sec channels on 8 simultaneous data streams. So, the ratios quoted seem reasonable to me. Hugh LaMaster, m/s 233-9, UUCP ames!lamaster NASA Ames Research Center ARPA lamaster@ames.arc.nasa.gov Moffett Field, CA 94035 Phone: (415)694-6117
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!cs.utexas.edu!sun-barr!ames!ames.arc.nasa.gov!lamaster From: lamaster@ames.arc.nasa.gov (Hugh LaMaster) Newsgroups: comp.arch Subject: Re: DMA on RISC-based systems Message-ID: <26636@ames.arc.nasa.gov> Date: 8 Jun 89 16:18:47 GMT References: <46500067@uxe.cso.uiuc.edu> <181@dg.dg.com> <185@dg.dg.com> <8479@june.cs.washington.edu> <1213@ttds.UUCP> Sender: usenet@ames.arc.nasa.gov Organization: NASA - Ames Research Center Lines: 24