Re: Process hangs on blk_congestion_wait copying large file to cifs filesystem

[Jens Axboe <axboe@suse.de>]

On Fri, May 28 2004, Nuno Ferreira wrote:
> On Qui, 2004-05-27 at 16:45 +0100, Nuno Ferreira wrote:
> > Hi,
> > I'm trying to copy a large file (200Mb or bigger) from an ext3
> > filesystem to a windows share mounted using CIFS and the cp process
> > hangs, sometimes for a long time (several minutes).
> > Calling ps, I can see that it's blocking on blk_congestion_wait.
> > 
> > Trying to edit a file on the same ext3 filesystem using vi blocks on the
> > same function. However, during that that same time that vi and cp were
> > blocked, I was able to do a "find /usr/share/doc" and it completed
> > normally, in a few seconds.
> > 
> > Eventually the copy succeeds but it takes a long time (20 minutes to
> > copy 200Mb) and the computer is unusable during most of that time.
> > 
> > This is copying from my laptop (IDE disk), the network card is a RTL8139
> > using 8139cp drivers.
> > 
> > Is someone seeing a similiar problem? What extra info is needed to debug
> > it?
> 
> Mmm, anyone with a similar problem? What should I do, make a profile
> like explained in Documentation/basic_profiling.txt or is the above
> information about the function where the processes are "stuck" enough?
> One thing I forgot to mention, during the several minutes the processes
> are stuck on that function there is no disk activity, so it's not the
> processes being starved. In fact, there is no other activity on the
> machine apart from the copy.

A sysrq-t back trace of that process would be interesting to see.

-- 
Jens Axboe