Re: Abysmal PATA IDE performance

[Stephen Clark <Stephen.Clark@seclark.us>]

Stephen Clark wrote:

>Tejun Heo wrote:
>
>  
>
>>Stephen Clark wrote:
>>[--snip--]
>> 
>>
>>    
>>
>>>ata1: SATA max UDMA/133 cmd 0x1F0 ctl 0x3F6 bmdma 0xFFA0 irq 14
>>>scsi0 : ata_piix
>>>Synaptics Touchpad, model: 1, fw: 6.1, id: 0xa3a0b3, caps: 0xa04713/0x10008
>>>input: SynPS/2 Synaptics TouchPad as /class/input/input1
>>>ATA: abnormal status 0x7F on port 0x1F7
>>>ata2: PATA max UDMA/100 cmd 0x170 ctl 0x376 bmdma 0xFFA8 irq 15
>>>scsi1 : ata_piix
>>>ata2.00: ATA-6, max UDMA/100, 117210240 sectors: LBA48
>>>ata2.00: ata2: dev 0 multi count 16
>>>usb 2-2: new low speed USB device using uhci_hcd and address 3
>>>ata2.01: ATAPI, max UDMA/33
>>>ata2.00: configured for UDMA/33 <==== why isn't this 66 or 100 ?
>>>   
>>>
>>>      
>>>
>>See below.
>>
>> 
>>
>>    
>>
>>>===============****
>>>usb 2-2: configuration #1 chosen from 1 choice
>>>input: Logitech USB-PS/2 Trackball as /class/input/input2
>>>input: USB HID v1.00 Mouse [Logitech USB-PS/2 Trackball] on
>>>usb-0000:00:1d.1-2
>>>ata2.01: configured for UDMA/33 <=========== is this related to the
>>>following 2 lines? ====
>>>   
>>>
>>>      
>>>
>>Nope,
>>
>> 
>>
>>    
>>
>>> Vendor: ATA       Model: HTS721060G9AT00   Rev: MC3O
>>> Type:   Direct-Access                      ANSI SCSI revision: 05
>>>SCSI device sda: 117210240 512-byte hdwr sectors (60012 MB)
>>>sda: Write Protect is off
>>>sda: Mode Sense: 00 3a 00 00
>>>SCSI device sda: drive cache: write back
>>>SCSI device sda: 117210240 512-byte hdwr sectors (60012 MB)
>>>sda: Write Protect is off
>>>sda: Mode Sense: 00 3a 00 00
>>>SCSI device sda: drive cache: write back
>>>sda: sda1 sda2
>>>sd 1:0:0:0: Attached scsi disk sda
>>>   
>>>
>>>      
>>>
>>The above is for ata2.00.
>>
>> 
>>
>>    
>>
>>> Vendor: HL-DT-ST  Model: DVDRAM GMA-4082N  Rev: HJ02
>>> Type:   CD-ROM                             ANSI SCSI revision: 05
>>>   
>>>
>>>      
>>>
>>And, this for ata2.01.
>>
>>PATA devices occupying the same channel literally share the cable, and 
>>the driver needs to configure PIO mode of both devices to the slowest of 
>>the two (PIO mode is always configured regardless of actual transfer 
>>mode).  UDMA mode doesn't save such restriction, so devices can be 
>>configured to its own maximum transfer mode.
>>
>>libata, until recently, simply used the slowest max transfer mode for 
>>both PIO and UDMA modes (MWDMA too).  So, that's what's happening to 
>>you.  Your cdrom's max UDMA mode is UDMA/33, so libata is using it for 
>>both devices on the channel.  Recent kernels (2.6.19-rcX) don't have 
>>this restriction.  Give 2.6.19-rc5 a shot.
>>
>> 
>>
>>    
>>
>Hi Tejun,
>
>Thanks for the info, I had started looking at the libata code but hadn't 
>progressed very far.
>
>Steve
>
>  
>
Hi all,

using 2.6.19-rc5 did give me udma 100 for my harddrive and a xfer rate 
of 44mbps.

thanks to all who offered advice.

Steve

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