Re: Serial ATA (SATA) for Linux status report

From: Jon Burgess
Date: Thu Dec 04 2003 - 13:04:56 EST

**Jeff Garzik wrote:
> Intel ICH5
> drivers/ide driver status: Production, but see issue #1, #2.
> Issue #2: Excessive interrupts are seen in some configurations.

I can reproduce this easily in my current setup. It looks like the chipset is generating some unexpected IRQ's when after performing the hdparm drive setting ioctl()'s.

More details are below, let me know if you need any more.

Gigabyte 8IG1000Pro (Intel ICH5)
2 x Parallel IDE drives on PATA IDE primary
2 x DVD drives on PATA IDE secondary
1 x Seagate 80GB SATA drive on SATA0

Linux-2.6.0-test10, using drivers/ide driver

The Root fileystem is currently on one of the parallel IDE drives, and the SATA doesn't get used much (yet). The PC boots and vmstat shows everything is OK.

Running an hdparm command on the drive causes an IRQ storm, reported by vmstat at ~ 100k IRQ/s. I think that "hdaprm -S 128 /dev/hde" will trigger it, but I can't remember for certain.
Performing another access to the drive, e.g. umount /dev/hde, clears the problem.
It is 100% repeatable, i.e. doing the hdparm makes it happen again, then mounting the drive will clear it.

I put some extra debug in the ide_intr routine and found that there was a storm of interrupts around when the partition table was being read (the "drive_check_ready()" check was failing continuously for a while). Afterwards there were times when lots of IRQs happened when "handler" was NULL. It looks like the chipset might be generating some extra IRQ's which the existing code isn't expecting. Doing another access on the drive looks like it is enough to clear whatever interrupt is pending.


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