Re: PDC20265 IDE controller trouble

[Rene Rebe]

Hi.

This is on a AMD K6-2 350Mhz, 128MB RAM, on a Ali Aladin5 based Gigabyte board
3x IBM DTLA 40GB discs on a Promisse TX2 Ultra 100 in a PCI slot.

Single transfer to one disk:
server1:~ # hdparm -tT /dev/ide/host2/bus0/target0/lun0/disc

/dev/ide/host2/bus0/target0/lun0/disc:
 Timing buffer-cache reads:   128 MB in  2.12 seconds = 60.38 MB/sec
 Timing buffered disk reads:  64 MB in  2.86 seconds = 22.38 MB/sec

Dual transfer to disks on sperated channels (values per disk):
server1:~ # hdparm -tT /dev/ide/host2/bus0/target0/lun0/disc

/dev/ide/host2/bus0/target0/lun0/disc:
 Timing buffer-cache reads:   128 MB in  4.13 seconds = 30.99 MB/sec
 Timing buffered disk reads:  64 MB in  4.66 seconds = 13.73 MB/sec

Dual transfer to disks on the same channel (values per dics):
server1:~ # hdparm -tT /dev/ide/host2/bus0/target1/lun0/disc

/dev/ide/host2/bus0/target1/lun0/disc:
 Timing buffer-cache reads:   128 MB in  4.44 seconds = 28.83 MB/sec
 Timing buffered disk reads:  64 MB in  8.36 seconds =  7.66 MB/sec

Hey! This might be the cause for the slowdown I reported in another
Raid5 / ReiserFS thread!!

Is this an general IDE issue or is some queueing code in the kernel
rather bad/slow for this task???

On Sat, 15 Dec 2001 18:35:29 +0100 (MET)
Jurij Smakov <[e-mail]> wrote:

> Hi!
> 
> Recently I've got an Asus TUSL2 motherboard, which has an extra Promise
> IDE RAID controller with a PDC20265 chip. I've connected two IBM 60 GB
> disks to it (one disk per channel). I am using kernel 2.4.17-pre8
> (with CONFIG_BLK_DEV_PDC202XX=y and with/without CONFIG_PDC202XX_BURST=y),
> which nicely detects the extra controller and both disks, hde and hdg. If
> I test the writing and reading speed (hdparm -t, dd if=/dev/zero of=test
> ...) separately for each disk, I get the expected figures, like 36-37
> MB/sec for reading, about 30 MB/sec for writing. If, however, I try to
> write simultaneously to both disks, the performance drops drastically. The
> rate for writing is then something like 3.5 MB/sec (!). I wonder if anyone
> have seen anything like that or might have any ideas on how to solve the
> problem.
> 
> Suspecting the hardware, I've posted this message to
> comp.os.linux.hardware first, but no one have seen such a behaviour. I
> have also tried different sets of IDE cables.
> 
> Best regards and TIA,
> 
> 
> Jurij.
> 
> P.S. Please cc responses to me, because I'm not on the list.
> 
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k33p h4ck1n6
  René

-- 
René Rebe (Registered Linux user: #248718 <http://counter.li.org>)

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