Re: Counter-kludge for 2.5.x hanging when writing to block device

[Jens Axboe]

On Tue, Jun 03 2003, Andrew Morton wrote:
> > Does something like this work? Andrew, what's the point of doing the
> > wait if the queue isn't congested?!
> 
> We need to wait until the amount of dirty memory in the machine is below
> the designated limits.  This is unrelated to queue congestion.  The way the
> logic is now we can have 256 megs worth of requests queues on a 32M machine
> and everything throttles and clamps as intended.
> 
> 
> There are several things wrong with blk_congestion_wait(), including:
> 
> a) it should be called throttle_on_io()

Well...

> b) it should check that there are still requests in flight after parking
>    itself on the waitqueue rather than relying on the timeout.

This is important, would be much nicer to pass in the backing dev. This
is a big problem, imho. It's broken right now.

> As for Adam's hang: dunno.  I and many others have run mkfs and dd an
> unbelievable number of times.  He needs to debug it more.

Agree

-- 
Jens Axboe