On 12 Mar 2006, at 19:02, David Wilson wrote:
> Hi folks,
>> We have a dual 2.8ghz Xeon server with 2gb RAM running vanilla
> which is seeing some really odd IO behaviour. I've always been aware
> that the machine felt slightly more sluggish than it should have, but
> upon running an extremely simple UPDATE on 80,000 or so rows in
> PostgreSQL last night, the machine crapped itself and jumped to a load
> of 8.0.
>> For comparison, the same UPDATE runs on the same dataset on the same
> version of PostgreSQL on a single CPU 2.8ghz P4 FreeBSD 4.10
> machine in
> slightly less time, and not even pushing the load past 0.2.
Cannot really compare against another OS, at least you know the hardware
should handle it.
> The filesystems are ext3.
>> The load isn't caused by userspace, indeed PostgreSQL sits at 6%
> utilisation for the most part, as the machine load climbs
So do you feel its a SATA bug?
If so, have you tried another kernel/driver?
>> The only thing I can think of is having the hosting company pull up
> BIOS and turn off hyperthreading, something I've been meaning to do
> various other reasons anyway.
Try "noht" to disable Hyperthreading in your bootloader.
You may also wish to try "noapic"
> Linux 126.96.36.199 #1 SMP Fri Jan 20 19:47:58 GMT 2006 i686
You may also wish to see if the issue occurs with a 2.4 kernel.
> scsi0 : ata_piix
> ATA: abnormal status 0x7F on port 0xC407
> ata1: SATA max UDMA/133 cmd 0xC800 ctl 0xC482 bmdma 0xC000 irq 17
> SCSI device sda: 586072368 512-byte hdwr sectors (300069 MB)
>> Does anyone have any pointers? Thanks,
When the issue occurs, try running iostat on the device to see if its
really an I/O issue.
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