Date: Tue, 31 Aug 1999 21:52:25 +0200 (CEST) From: Soren Schmidt <sos@freebsd.dk> To: street@iname.com (Kevin Street) Cc: current@FreeBSD.ORG Subject: Re: HEADS UP! ATA driver (atapi DMA).. Message-ID: <199908311952.VAA80929@freebsd.dk> In-Reply-To: <87btbnetgc.fsf@mired.eh.local> from Kevin Street at "Aug 31, 1999 1:44: 3 pm"
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It seems Kevin Street wrote: > Two things I've noticed: > 1) my cdrom delivers about 2M/s which is the same as before DMA. Is > the improvement only in cpu usage or should I be seeing a speed > improvement too? Depends.. There are many factors involved here, using DMA only lowers the CPU usage, and will enable faster transfers if the problem was that the CPU was saturated with the PIO transfer. It gave about double the transfer rate on my old P6 based maschine, because the CPU drain was the limitting factor. Most modern CDROM are variable speed, and you will see varying rates depending on the quality of the media. > 2) I can crash my system (sometimes a panic, sometimes a freeze) with: > dd if=/dev/racd0c of=/dev/null bs=1m count=1 > > I could do bs=1m before the DMA code went in. > > If the system freezes I see: > atapi_error: READ_BIG - timeout error = 00 > <long pause> > the dd puts out a message about transferring 0 records > ata1: master: timeout waiting to give command s = d8 e = 00 Yup I know of that one, not sure how to fix it (right) yet... -Søren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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