Messages in this thread | | | From | Benno Senoner <> | Subject | Re: disk corruptions on "tuned" disks Was: APM killing low-latency performance on BX mainboard | Date | Thu, 11 Nov 1999 03:06:20 +0100 |
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On Thu, 11 Nov 1999, Dan Hollis wrote: > > thanks, but what is the exact problem source , DMA or unmask IRQ ? > > DMA > > > I'm watching DVDs for hours ( DMA enabled) without any lockups. > > It may be ultra dma only bug. Im not sure. My DVDROM and CDROM both > support udma.
I don't played with UDMA on CDROMS, only simple DMA. I don't care about a potential UDMA bug, simple DMA solves all latency problems, and the performance difference between DMA and UDMA on a CDROM drive is almost zero. (since the CDROM is the bottleneck).
The command I usually use to tune the CDROM is : hdparm -u 1 -c 1 -d 1 /dev/hdc
it is a cheap MASHITA 6x DVD drive: [root@localhost benno]# cat /proc/ide/ide1/hdc/settings name value min max mode ---- ----- --- --- ---- breada_readahead 4 0 127 rw dsc_overlap 0 0 1 rw file_readahead 72 0 2097151 rw io_32bit 1 0 3 rw keepsettings 0 0 1 rw max_kb_per_request 122 1 127 rw nice1 1 0 1 rw pio_mode write-only 0 255 w slow 0 0 1 rw unmaskirq 1 0 1 rw using_dma 1 0 1 rw
> > > But are you sure that every ATAPI CDROM drive on the planet > > has this hardware flaw. > > Its the controller not the CDROM at fault
are you sured that the BX chipset is flawed ? It seems to work well.
> > > I stressed my CDROM drives quite a bit, and was unable to lock up the box. > > What controller and what drives
Mainboard Gigabyte GA 6BXD (dual) with BX chipset.
> > > How is this handled my other OSes ? > > They dont run DMA.
Wrong: try to dig on deja.com searching articles about DVD software playback on windoze: for most people it is almost impossible to get skipfree video without DMA.
> > > > Promise Ultra66. No DMA on CDROM/DVDs. It just wont work. At all. > > PS: why should recent ATAPI CDROM let you set the DMA mode, when they > > know that it could lead to problems ? > > Its the controller not the CDROM at fault
I was wondering how much % of the controllers are faulty in this respect.
> > -Dan
Benno.
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