On Mon, Aug 05, 2013 at 10:50:16AM +0200, Dawid Stawiarski wrote: > Dnia Piątek, 2 Sierpnia 2013 17:47 J. Bruce Fields napisał(a) > > On Fri, Aug 02, 2013 at 04:37:57PM +0200, Dawid Stawiarski wrote: > > > W dniu 02.08.2013 15:12, Jeff Layton pisze: > > > >Typically, a stack trace like that indicates that the process is > > > >waiting for the server to respond. The first thing I would do would be > > > >to ascertain whether the server is actually responding to these > > > >requests. > > > > > > > > > > The same share is accessible on other nodes, so the problem involves > > > only one of the nodes (completly random) at a time. > > > > It's still conceivable that a server problem could cause it to stop > > responding to calls only from a single client--it'd be useful if > > possible to check a trace to see if that's what's happening. If the > > traffic is really huge then capturing and analyzing a good trace may be > > difficult. > > I've managed to capture network traffic on client side, when the problem starts. > It seems like: > 0. operation SETATTR before problem works as charm (attached for reference) > 1. retransmission happens very fast after sending 3 packets for WRITE operation > 1a. linux is not using jumbo frame (3 packets of ~1K size instead of one) > 2. linux ignores the ACK received after retransmission (actually it's SACK for the third packet) I don't see any SACK? But yes I see it appears to be ACKing a sequence number that should cover the segment the client keeps retransmitting. And I don't know what would cause that. Might be worth asking networking folks? (netdev@xxxxxxxxxxxxxxx). --b. > 3. both client and server start to retransmit their packets > > what happens next (not visible in the pcap attached) is that the server sends RST after some time, and client starts new connection - after that, things start to work normally again. So maybe, it's more general problem with TCP stack and not NFS itself? > > D. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
