Path: utzoo!attcan!uunet!cs.utexas.edu!csd4.csd.uwm.edu!mailrus!ames!ncar!unmvax!ogccse!orstcs!jacobs.cs.orst.edu!willieb From: willieb@jacobs.cs.orst.edu (Willie Brown) Newsgroups: comp.sys.amiga Subject: How to measure disk speed Keywords: hard disk,Supra Message-ID: <12218@orstcs.CS.ORST.EDU> Date: 25 Aug 89 04:31:47 GMT Sender: usenet@orstcs.CS.ORST.EDU Reply-To: willieb@jacobs.cs.orst.edu (Willie Brown) Organization: Oregon State University - CS - Corvallis Oregon Lines: 80 In Article: >From: johnl@tw-rnd.SanDiego.NCR.COM (John Lindwall) >Subject: How to measure disk speed >Date: 8 Aug 89 01:40:09 GMT >I have a Quantum 80S, Supra 4x4 controller on my A1000. I wanted disk >performance figures and so I ran diskperf3.0 and perftest. With diskperf >I get between 200K/sec reads and 90K/sec writes all the way up to 280K/sec >reads and 150K/sec writes. Perftest results were 200K/sec reads and >85K/sec writes. Clark in Tech Support replys: The benchmark program we use at Supra is DiskPerf2. I haven't run any comparisons with DiskPerf3, but I have been told the results are fairly close. As for the original DiskPerf, it was not very accurate and it didn't properly release some of the locks it obtained from AmigaDOS. Perftest is not testing just disk performance, but disk performance as it is effected by overscan. When you compare Perftest results with DiskPerf2 results, you may be comparing apples and oranges. >When Supra quotes 326K/sec (on the A500 interface in their full page ads in >AmigaWorld) do they use disperf or what? I assume they kludge it to get >the best results (buffers = 100K?!? maybe). As to the discrepancy between your benchmarks and ours, we are only about 15% apart. So that we can consistently replicate our results, we make every effort not to kludge anything. We always benchmark using a drive that has been freshly formatted with the DEFAULT parameters and divided into two equal partitions. We run our test on the second partition, which always starts out empty. We keep the number of additional task running to those that are started from a standard 1.3 Startup-Sequence, plus SupraMount. We redirect the output of our benchmark to a new file in the RAM disk. We don't do anything to the system while the benchmark is running, including moving the mouse or clicking a button. >What is the purpose for having the multiple buffer runs in diskperf? >If I want to gain the greatest speed am I supposed to up my buffers in the >mountlist (or SupraEdit screen)? I don't want to waste 32K for a large >buffer for such a small increase. As to buffers, this is a common point of confusion. There are two distinctly separate types of buffers that are called into play when doing a benchmark. The first are the cache buffers that are created when the drive is mounted, and that are maintained by AmigaDOS. These buffers speed up accesses when repeatedly reading or writing to the same few (number of buffers) sectors. These are the same sectors effected by the AddBuffers command in the 'c' directory. The buffers referred to by benchmark programs are not AmigaDOS cache buffers. Rather, these are contiguous read or write buffers that are allocated and freed by the benchmark, and whose address is passed to AmigaDOS when the transfer function is called. As such, you probably won't see much direct correlation between the number of cache buffers and size of the buffers used by a benchmark. Usually the only thing that improves noticeably when increasing AmigaDOS buffers past 30 is the number of files that can be deleted per second. Big deal! >A question for Supra owners: has anyone tried to up the MaxTransfer value? >The Supra software sets it to 64K, but I believe a larger number (or none if >possible) would provide faster performance. Is it reliable? As to MaxTransfer, yes you could bump it up to 128K or even 256K and get some performance boost on the larger file transfers. Frankly, unless you do extensive work with very large files or spend your days writing benchmark programs, I doubt you'd ever notice the difference. As to the low side, I've never seen anybody set MaxTransfer lower than 4K. I just don't know what the file system would do with a drive that had no MaxTransfer. Regards, Clark Supra Tech Support --------------------------------------------------------------- Willie Brown Usenet: willieb@jacobs.cs.orst.edu Supra Corp Phone: (503) 967-9081 (Tech Support) Albany, OR USA Fax: (503) 926-9370 ---------------------------------------------------------------