Messages in this thread | | | Date | Fri, 14 Aug 2009 22:10:38 +0100 | From | Alan Cox <> | Subject | Re: How to disable DMA for compact-flash disk? |
| |
> This worked fine, but now I'm having some more issues. Using libata is 1/2 > as fast as using IDE mode. I *think* the problem might be that libsata > may not be using 32-bit PIO mode, but I'm not certain of that. It seems > that ide mode uses PIO2 v/s PIO4 for libsata too.
As of 2.6.29 libata doesn't use 32bit PIO (it shouldn't make a difference for most chipsets but it does for some). 2.6.30 does for some and you can turn it on for others if you want to test by inheriting ata_bmdma32_port_ops instead of ata_bmdma_port_ops
> hdb: Ridata CF, CFA DISK drive > hdb: host max PIO5 wanted PIO255(auto-tune) selected PIO2 > hdb: host max PIO5 wanted PIO255(auto-tune) selected PIO2
Very odd it picked PIO2, but the numbers you quote for hdparm doesn't sound like PIO2 so its hard to guess.
> ata1.01: configured for PIO4
So libata picked a faster rate (PIO4 is the fastest the controller is properly specced for according to my docs - it probably can do PIO5 (CF specific))
> /dev/sda1: > Timing cached reads: 280 MB in 2.00 seconds = 139.98 MB/sec > Timing buffered disk reads: 10 MB in 3.69 seconds = 2.71 MB/sec
Would be very interested to know if bmdma32_port_ops gives you the speed.
| |