Re: [feature] automatically detect hung TASK_UNINTERRUPTIBLE tasks

Mark Lord
2007-12-05T22:31:39Z

Arjan van de Ven wrote:
> On Mon, 3 Dec 2007 11:27:15 +0100
> Andi Kleen <andi@firstfloor.org> wrote:
>
>>> Kernel waiting 2 minutes on TASK_UNINTERRUPTIBLE is certainly
>>> broken.
>> What should it do when the NFS server doesn't answer anymore or
>> when the network to the SAN RAID array located a few hundred KM away
>> develops some hickup? Or just the SCSI driver decides to do lengthy
>> error recovery -- you could argue that is broken if it takes longer
>> than 2 minutes, but in practice these things are hard to test
>> and to fix.
>>
>
> the scsi layer will have the IO totally aborted within that time anyway;
> the retry timeout for disks is 30 seconds after all.
..

Mmm.. but the SCSI layer may do many retries, each with 30sec timeouts..