Messages in this thread |  | | Date | Tue, 9 Apr 2002 13:27:48 -0700 (PDT) | From | Andre Hedrick <> | Subject | Re: PROMBLEM: CD burning at 16x uses excessive CPU, although DMA is enabled |
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On Tue, 9 Apr 2002, Roger Larsson wrote:
> On tisdagen den 9 april 2002 12.01, Anssi Saari wrote: > > On Mon, Apr 08, 2002 at 06:02:55PM -0400, Mark Hahn wrote: > > > I think someone else already pointed out that doing > > > a kernel profile would be good. strace would also > > > be quite useful, even just the -c form. > > > > Here it is: > > > > With unmaskirq=1 first: > > > > > > 49 handle_IRQ_event 0.5104 > > 239 file_read_actor 2.4896 > > 3324 default_idle 69.2500 > > 20097 ide_output_data 104.6719 > > Hey, what is this? > > Comment of the function is: > "This is used for most PIO data transfers *to* the IDE interface" > (see /drivers/ide/ide.c:426) > Has it reverted to PIO mode?
This is because there are not a proper and correct state diagram data handler set for ATAPI, period. Initially the driver evolved out of PIO calls to the PACKET_COMMAND opcode for the ATA command set. Since there has been zero updates/attempts to create a proper ATAPI/ASPI by anyone, you can expect PIO transactions.
Who knows once I finally have taskfile completed and the kernel fixed to not violate the basics of hardware atomic for storage devices, I may fix all of the atapi/aspi transport. It is a real mess to grunt through all the docs. However, I suspect I could get some help (co-author a standard's proposal) with the original author to outline and create a 500+ page techincal referrence guide. So if there are any companies want to fund such an adventure, please let me know off-line.
Understand that only in PIO can you be sure of how much data you could get from a device, argh it still s a pig in a poke.
Cheers,
Andre Hedrick LAD Storage Consulting Group
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