Re: [RFC][PATCH] at91_ide driver

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello, I wrote:

>>>> the PIO transfer speeds (very significantly) though I'm not sure of 
>>>> the current state of affairs...

>>> 16bit only performance is identical (as you'd expect)

>>   Well, I don't know what to expect, having seen figures like 0.5 (or 
>> 1.5) MB/s cited on this list...

>   Instead of going to bed, I tried booting FC8 (2.6.23.y) off DVD in 
> rescue mode and suppressing libata's DMA use: hdparm -t topped at around 
> 1 MB/s from both SATA hard drive and PATA DVD drive with sata_sil driven 
> the former and pata_atiixp the latter... I wasn't able to compare 
> results with IDE core of course.

>>> identical with the 32bit pio patches applied

>> 32bit is now

>>   Hm, I didn't realize 32-bit I/O really can really boost the IDE 
>> speed. I vaguely remember (or misremember) benchmarking drives under 
>> DOS (many years ago) with and without 32-bit access enabled in the 
>> BIOS Setup and not seeing any significant differences. Perhpas it's 
>> worth to re-benchmark this in Linux if I find the time...

>   With hdparm being able to control that via its -c option when using 
> IDE driver, it shouldn't take much time...

    Here's the results I got on my work PC having 2 hard disks on 82801DB, 
still running the ancient RH9 (which included hdparm 5.5):

[root@wasted etc]# /sbin/hdparm -i /dev/hda

/dev/hda:

  Model=ST380011A, FwRev=3.06, SerialNo=5JV4FZNT
  Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
  BuffType=unknown, BuffSize=2048kB, MaxMultSect=16, MultSect=16
  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
  IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
  PIO modes:  pio0 pio1 pio2 pio3 pio4
  DMA modes:  mdma0 mdma1 mdma2
  UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
  AdvancedPM=no WriteCache=enabled
  Drive conforms to: ATA/ATAPI-6 T13 1410D revision 2:  1 2 3 4 5 6

[root@wasted etc]# /sbin/hdparm -c /dev/hda

/dev/hda:
  IO_support   =  0 (default 16-bit)

[root@wasted etc]# /sbin/hdparm -d0 -p4 /dev/hda

/dev/hda:
  setting using_dma to 0 (off)
  using_dma    =  0 (off)

/dev/hda:
  attempting to set PIO mode to 4

[root@wasted etc]# /sbin/hdparm -t /dev/hda

/dev/hda:
  Timing buffered disk reads:  64 MB in 22.65 seconds =  2.83 MB/sec

[root@wasted etc]# /sbin/hdparm -c1 /dev/hda

/dev/hda:
  setting 32-bit IO_support flag to 1
  IO_support   =  1 (default 32-bit)

[root@wasted etc]# /sbin/hdparm -t /dev/hda

  Timing buffered disk reads:  64 MB in 18.19 seconds =  3.52 MB/sec

[root@wasted etc]# /sbin/hdparm -i /dev/hdb

/dev/hdb:

  Model=Maxtor 2F030J0, FwRev=VAM51JJ0, SerialNo=F11HZPNE
  Config={ Fixed }
  RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57
  BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16
  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=60056543
  IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
  PIO modes:  pio0 pio1 pio2 pio3 pio4
  DMA modes:  mdma0 mdma1 mdma2
  UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 udma6
  AdvancedPM=yes: disabled (255) WriteCache=enabled
  Drive conforms to: (null):  1 2 3 4 5 6 7

[root@wasted etc]# /sbin/hdparm -c /dev/hdb

/dev/hdb:
  IO_support   =  0 (default 16-bit)

[root@wasted etc]# /sbin/hdparm -d0 -p4 /dev/hdb

/dev/hdb:
  setting using_dma to 0 (off)
  using_dma    =  0 (off)

/dev/hdb:
  attempting to set PIO mode to 4

[root@wasted etc]# /sbin/hdparm -t /dev/hdb

/dev/hdb:
  Timing buffered disk reads:  64 MB in 20.80 seconds =  3.08 MB/sec

[root@wasted etc]# /sbin/hdparm -c1 /dev/hdb

/dev/hdb:
  setting 32-bit IO_support flag to 1
  IO_support   =  1 (default 32-bit)

[root@wasted etc]# /sbin/hdparm -t /dev/hdb

  Timing buffered disk reads:  64 MB in 12.69 seconds =  5.04 MB/sec

    As you can see, although the speed increase can certainly be seen, it's 
not really that big for the (cheapo :-) Seagate drive while Maxtor 
demonstrated 1.6x increase. I need to try somewhat newer kernel though (don't 
want to reboot to CentOS)...

MBR, Sergei