IDE performance drop between 2.4.23 and 2.6.0

[Jean-Luc Fontaine]

Using hdparm -Tt /dev/hdb:

on 2.4:
 Timing buffer-cache reads:   168 MB in  2.01 seconds =  83.58 MB/sec
 Timing buffered disk reads:   44 MB in  3.12 seconds =  14.10 MB/sec
on 2.6:
 Timing buffer-cache reads:   172 MB in  2.02 seconds =  84.95 MB/sec
 Timing buffered disk reads:   34 MB in  3.08 seconds =  11.04 MB/sec

Note the big drop of of 3 MB/sec on disk reads.

dmesg (edited) gives:

on 2.4:
 VP_IDE: VIA vt82c586b (rev 41) IDE UDMA33 controller on pci00:07.1
 hdb: IC35L040AVVN07-0, ATA DISK drive
 hdb: 80418240 sectors (41174 MB) w/1863KiB Cache, CHS=79780/16/63, 
UDMA(33)
on 2.6:
 VP_IDE: VIA vt82c586b (rev 41) IDE UDMA33 controller on pci0000:00:07.1
 hdb: IC35L040AVVN07-0, ATA DISK drive
 hdb: 80418240 sectors (41174 MB) w/1863KiB Cache, CHS=65535/16/63, 
UDMA(33)

hdparm -i output is identical between the 2 kernels and hdparm settings 
are identical as follows (except cylinders as above):

 Model=IC35L040AVVN07-0, FwRev=VA2OAG0A, SerialNo=VNP210B2RAP0TB
 Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=52
 BuffType=DualPortCache, BuffSize=1863kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=80418240
 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=yes: disabled (255) WriteCache=enabled
 Drive conforms to: ATA/ATAPI-5 T13 1321D revision 1:

 multcount    = 16 (on)
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 79780/16/63, sectors = 80418240, start = 0

I noticed a difference in dmesg:
on 2.4:
 Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4
on 2.6:
 Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2

Could that make a difference?

Please let me know if you'd like me to run more tests, patch kernels, 
..., anything to regain the performance.


Many thanks in advance,

--
Jean-Luc Fontaine

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/