Tejun Heo wrote: > Simon Farnsworth wrote: >> Tejun Heo wrote: >>> Simon Farnsworth wrote: >>>> Tejun Heo wrote: >>>>> Simon Farnsworth wrote: >>>>>> Just a thought; is it possible to trigger libata EH from userspace? If >>>>>> so, we could write a small utility to disable write cache, then force EH >>>>>> to detect the change. >>>>> That's automatically done. libata snoops cache on/off and triggers >>>>> revalidation but you can request manual rescan by echoing "- - -" to >>>>> /sys/class/scsi_host/hostX/scan. >>>>> >>>> Would it be worth changing our code to do "hdparm -W1 /dev/sda && hdparm >>>> -W0 /dev/sda", or would this not show anything. The lack of revalidation >>>> on some drives is what's worrying me a little here. >>> Revalidation happens after cache property is changed successfully. What >>> happens if you request manual rescan while the drive is not repsponding? >>> >> The 30 second freeze happens when we request manual rescan. We do >> revalidate once the freeze is over, though; dmesg follows: > > Can you post dmesg with printk timestamps turned on? > Sorry for the delay in responding; Turning on printk timestamps is enough to fix the problem, and stop the stall from happening. We'll be rebasing to the newest Fedora 7 kernel soon (next 3 months), and I've changed our kernel build process to turn on printk timestamps. If it still happens then, I'll get you a dmesg with timestamps. -- Simon Farnsworth - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
