Skip to contentSkip to conversation

SCSI Controler SCRU32 becomes realy slow on the latest kernels

DISCUSSION Hartmut Manz 2 participants 2 messages Dec 7, 2006 – Dec 10, 2006 SCSI

lore
Share & tools
lore

Hartmut Manz

author
#0 lore raw

I am using here 2 machines with the ICP Vortex SCSI-Controler SCRU32 for some years now.

After switching one machine from Debian 3.1 (sarge, with Kernel 2.6.8) to the upcoming Debian 4.0 (etch with Kernel 2.6.17 or 2.6.18) I have noticed that my scsi-devices become very slow while there is also a dramatical increase in the sys time needed for I/O operations.

The machine is a dual processor Xeon system (2 * 2.2 GHz) with 2 GB memory. The used scsi drives are seagate R10k and R15k disks.

i.e. reading 1 GB from the first SCSI drive takes about:

xen-1:/var/log# time dd if=/dev/sda bs=256k count=4000 of=/dev/null
4000+0 records in
4000+0 records out
1048576000 bytes (1.0 GB) copied, 55.3079 seconds, 19.0 MB/s
real    0m55.361s
user    0m0.368s
sys     0m49.107s

There are two strange things:
1. The transfer rate is only 19 MB/sec what is very low for this machine. The expected value would be at least 50 MB/sec.

2. the system time is in the same range as the real time and thats realy annoying, on the old kernel the system time for such an operatin was about 7 sec.

Thanks for any help

Hartmut

Signature · 7 lines
-----------------------------------------------------------------------------
Hartmut Manz                                      WWW:    http://www.intes.de
INTES GmbH                                        Phone:  +49-711-78499-29
Schulze-Delitzsch-Str. 16                         Fax:    +49-711-78499-10
D-70565 Stuttgart                                 E-mail: [email protected]
      Gott spricht: Ich lasse dich nicht fallen und verlasse dich nicht.
------------------------------------------------------  Josua 1, 5b ---------
#1 lore raw
Quoted 13 lines · On Thu, 7 Dec 2006 14:28:44 +0100 Hartmut Manz <[email protected]> wrote:

I am using here 2 machines with the ICP Vortex SCSI-Controler SCRU32 for some years now.

After switching one machine from Debian 3.1 (sarge, with Kernel 2.6.8) to the upcoming Debian 4.0 (etch with Kernel 2.6.17 or 2.6.18) I have noticed that my scsi-devices become very slow while there is also a dramatical increase in the sys time needed for I/O operations.

The machine is a dual processor Xeon system (2 * 2.2 GHz) with 2 GB memory. The used scsi drives are seagate R10k and R15k disks.

i.e. reading 1 GB from the first SCSI drive takes about:

Quoted 8 lines
xen-1:/var/log# time dd if=/dev/sda bs=256k count=4000 of=/dev/null
4000+0 records in
4000+0 records out
1048576000 bytes (1.0 GB) copied, 55.3079 seconds, 19.0 MB/s
real    0m55.361s
user    0m0.368s
sys     0m49.107s

ouch.

Quoted 8 lines

There are two strange things:
1. The transfer rate is only 19 MB/sec what is very low for this machine. The expected value would be at least 50 MB/sec.

2. the system time is in the same range as the real time and thats realy annoying, on the old kernel the system time for such an operatin was about 7 sec.

It would help a lot of we can determine where the kernel is spending all this time. Can you please generate a kernel profile?

Start a large IO operation then, while it is running, run

#!/bin/sh
sudo opcontrol --stop
sudo opcontrol --shutdown
sudo rm -rf /var/lib/oprofile
sudo opcontrol --vmlinux=/boot/vmlinux-$(uname -r) sudo opcontrol --start-daemon
sudo opcontrol --start
sleep 10
sudo opcontrol --stop
sudo opcontrol --shutdown
sudo opreport -l /boot/vmlinux-$(uname -r) | head -50

(might need some adjustments for distro variation)

Thanks.