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From: Michael Sierchio on 20 Jun 2008 12:58 Steve O'Hara-Smith wrote: > Hmm lessee now DVD-ROM at 16x rate is somewhere around 20MB/s > whereas it's hard to get above about 8MB/s with PIO. Dropping to PIO will > reduce throughput to any fast drive (by a factor of 2-3 not 10 for optical > drives) but what is worse is that at maximum throughput it will use all > available CPU in interrupt response. You'll never see 20MB/s *throughput* from a DVD-ROM. Again, you're conflating transfer rate and throughput. I'm not suggesting that PIO is to be preferred, I was commenting that the hyperbole in the post that prompted my response was way out of line. - M
From: Steve O'Hara-Smith on 21 Jun 2008 03:27 On Fri, 20 Jun 2008 09:58:22 -0700 Michael Sierchio <kudzu-usenet2(a)tenebras.com> wrote: > Steve O'Hara-Smith wrote: > > > Hmm lessee now DVD-ROM at 16x rate is somewhere around 20MB/s > > whereas it's hard to get above about 8MB/s with PIO. Dropping to PIO > > will reduce throughput to any fast drive (by a factor of 2-3 not 10 for > > optical drives) but what is worse is that at maximum throughput it will > > use all available CPU in interrupt response. > > You'll never see 20MB/s *throughput* from a DVD-ROM. Again, you're > conflating transfer rate and throughput. I have seen 20 MB/s throughput from a DVD-ROM for the data in the outer 10% or so of the disc. That is what happens when the drive hits 16x speed so I am talking about real throughput speed media to memory. I've also seen it writing to a DVD +R for longer periods on a 20x drive that usually reaches 18x with the media I have to hand. I will grant you that average throughput across the disc is nowhere near 20MB/s. -- C:>WIN | Directable Mirror Arrays The computer obeys and wins. | A better way to focus the sun You lose and Bill collects. | licences available see | http://www.sohara.org/
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