Re: A unresponsive file system can hang all I/O in the system on linux-2.6.23-rc6 (dirty_thresh problem?)

Peter Zijlstra
2007-09-29T14:43:55Z

On Sat, 2007-09-29 at 20:28 +0800, Fengguang Wu wrote:
> On Sat, Sep 29, 2007 at 01:48:01PM +0200, Peter Zijlstra wrote:

> > On the patch itself, not sure if it would have been enough. As soon as
> > there is a single dirty inode on the list one would get caught in the
> > same problem as before.
>
> That should not be a problem. Normally the few new dirty inodes will
> be all cleaned in one go and there are no more dirty inodes left(at
> least for a moment). Hmm, I guess the new 'break' should be moved
> immediately after writeback_inodes()...
>
> > That is, if NFS_dirty+NFS_unstable+NFS_writeback > dirty_limit this
> > break won't fix it.
>
> In fact this patch exactly targets at this condition.
> When NFS* < dirty_limit, Chakri won't see the lockup at all.
> The problem was, there are only two 'break's in the loop, and neither
> one evaluates to true for his dd command.

Yeah indeed, when put in the loop, after writeback_inodes() it makes
sense.

No idea what I was thinking, must be one of those days... :-/