Compact Flash performance...

[Daniel J Blueman]

I have a SanDisk Extreme IV 4GB CF card, capable of 40MB/s read, but
am seeing 30MB/s read [1], connected directly to the IDE bus on my
ICH8 controller.

How can I find out if this would be a timing or configuration issue?
On 2.6.20.5 [2], the 120nS timing looks to be right [3], but perhaps
no multi-word transfer is hurting here...alas, it can't be enabled
with the libata subsystem and 'hdparm -m', so what else?

Daniel

--- [1]

# hdparm -t /dev/sdb
/dev/sdb:
Timing buffered disk reads:   94 MB in  3.05 seconds =  30.79 MB/sec

--- [2]

ata7: PATA max UDMA/100 cmd 0x000000000001bc00 ctl 0x000000000001b882
bmdma 0x000000000001b400 irq 17
ata7.00: CFA: SanDisk SDCFX-4096, HDX 4.04, max UDMA/66
ata7.00: 8027712 sectors, multi 0: LBA
ata7.00: configured for UDMA/66
ATA: abnormal status 0x7F on port 0x000000000001b807
scsi 6:0:0:0: Direct-Access     ATA      SanDisk SDCFX-40 HDX  PQ: 0 ANSI: 5
SCSI device sdb: 8027712 512-byte hdwr sectors (4110 MB)
sdb: Write Protect is off
sdb: Mode Sense: 00 3a 00 00
SCSI device sdb: write cache: disabled, read cache: enabled, doesn't
support DPO or FUA
SCSI device sdb: 8027712 512-byte hdwr sectors (4110 MB)
sdb: sdb1
sd 6:0:0:0: Attached scsi removable disk sdb

--- [3]

# hdparm -I /dev/sdb

/dev/sdb:

CompactFlash ATA device, with removable media
       Model Number:       SanDisk SDCFX-4096
       Serial Number:      116802D2807J3335
       Firmware Revision:  HDX 4.04
Standards:
       Supported: 4
       Likely used: 4
Configuration:
       Logical         max     current
       cylinders       7964    7964
       heads           16      16
       sectors/track   63      63
       --
       CHS current addressable sectors:    8027712
       LBA    user addressable sectors:    8027712
       device size with M = 1024*1024:        3919 MBytes
       device size with M = 1000*1000:        4110 MBytes (4 GB)
Capabilities:
       LBA, IORDY(may be)(cannot be disabled)
       Standby timer values: spec'd by Vendor
       R/W multiple sector transfer: Max = 4   Current = 0
       DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 *udma4
            Cycle time: min=120ns recommended=120ns
       PIO: pio0 pio1 pio2 pio3 pio4
            Cycle time: no flow control=120ns  IORDY flow control=120ns
Commands/features:
       Enabled Supported:
               Write cache
          *    CFA feature set
--
Daniel J Blueman
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