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[Xen-users] Very slow drives, I/O - DMA issues?

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Very slow drives, I/O - DMA issues?
From: "Lonny Selinger" <lonny@xxxxxxxxxxxxxxxxxxxxxxxx>
Date: Tue, 20 Feb 2007 16:38:01 -0600 (CST)
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I'm having some issues with Xen disk IO being almost unbearable. I've read
some other threads suggesting possibly the hardware did not get recognized
properly but I'm not seeing where that might be in dmesg.

First here are my hdparm results:

# hdparm -tT /dev/hda

 Timing cached reads:   1476 MB in  2.00 seconds = 737.13 MB/sec
 Timing buffered disk reads:   10 MB in  3.44 seconds =   2.90 MB/sec

# hdparm -tT /dev/hdb

 Timing cached reads:   1480 MB in  2.01 seconds = 738.15 MB/sec
 Timing buffered disk reads:    6 MB in  3.15 seconds =   1.91 MB/sec

Here are basically the drive type on another machine:

# hdparm -tT /dev/hda

 Timing cached reads:   1132 MB in  2.00 seconds = 565.80 MB/sec
 Timing buffered disk reads:  170 MB in  3.01 seconds =  56.57 MB/sec

Anyway ... here are some relivent lines from dmesg. Can anyone suggest what
might be causing the problem?

ide_disk: no version for "struct_module" found: kernel tainted.
Probing IDE interface ide0...
hda: WDC WD400JB-00ENA0, ATA DISK drive
hdb: WDC WD2000JB-32FUA0, ATA DISK drive
Probing IDE interface ide1...
hdd: HL-DT-ST GCE-8523B, ATAPI CD/DVD-ROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: max request size: 128KiB
hda: 78165360 sectors (40020 MB) w/8192KiB Cache, CHS=65535/16/63
hda: cache flushes not supported
 hda: hda1 hda2
hdb: max request size: 512KiB
hdb: 390721968 sectors (200049 MB) w/8192KiB Cache, CHS=24321/255/63
hdb: cache flushes supported
 hdb: hdb1
SCSI subsystem initialized
ACPI: PCI Interrupt Link [APC3] enabled at IRQ 18
ACPI: PCI Interrupt 0000:01:08.0[A] -> Link [APC3] -> GSI 18 (level, high) ->
IRQ 16
        <Adaptec 2940 Ultra SCSI adapter>
        aic7880: Ultra Wide Channel A, SCSI Id=7, 16/253 SCBs

device-mapper: 4.5.0-ioctl (2005-10-04) initialised: dm-devel@xxxxxxxxxx
kjournald starting.  Commit interval 5 seconds
EXT3-fs: mounted filesystem with ordered data mode.
hdc: ATAPI 48X DVD-ROM drive, 512kB Cache
Uniform CD-ROM driver Revision: 3.20
hdd: ATAPI 52X CD-ROM CD-R/RW drive, 2048kB Cache
NFORCE2: IDE controller at PCI slot 0000:00:09.0
NFORCE2: chipset revision 162
NFORCE2: not 100% native mode: will probe irqs later
NFORCE2: BIOS didn't set cable bits correctly. Enabling workaround.
NFORCE2: 0000:00:09.0 (rev a2) UDMA133 controller
NFORCE2: port 0x01f0 already claimed by ide0
NFORCE2: port 0x0170 already claimed by ide1
NFORCE2: neither IDE port enabled (BIOS)
forcedeth.c: Reverse Engineered nForce ethernet driver. Version 0.49.
ACPI: PCI Interrupt Link [APCH] enabled at IRQ 22
ACPI: PCI Interrupt 0000:00:04.0[A] -> Link [APCH] -> GSI 22 (level, high) ->
IRQ 17
PCI: Setting latency timer of device 0000:00:04.0 to 64
eth0: forcedeth.c: subsystem: 01043:80a7 bound to 0000:00:04.0
ACPI: PCI Interrupt Link [APCJ] enabled at IRQ 21
ACPI: PCI Interrupt 0000:00:06.0[A] -> Link [APCJ] -> GSI 21 (level, high) ->
IRQ 18
PCI: Setting latency timer of device 0000:00:06.0 to 64

I even tried to set DMA on the drives:
# hdparm -d1 /dev/hda

 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

Any help is greatly appreciated ... I'd love this machine to be useable :)


"The glass is neither half empty nor half full ... it is twice as big as it
needs to be"

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