Re: kern/41417 (WAPBL: hang on tstile)

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Jul 27, 2011 at 12:51:32PM +0200, Manuel Bouyer wrote:
> On Sun, Jul 17, 2011 at 11:23:40PM +0000, dholland%NetBSD.org@localhost wrote:
> > Synopsis: WAPBL: hang on tstile
> > 
> > State-Changed-From-To: open->feedback
> > State-Changed-By: dholland%NetBSD.org@localhost
> > State-Changed-When: Sun, 17 Jul 2011 23:23:40 +0000
> > State-Changed-Why:
> > please test HEAD
> 
> I've been running the rsync commands in a while(1) loop for more than 16 
> hours,
> and the system is still alive so it looks like it's fixed in HEAD.

Hum, but the rsync is very slow with a current kernel, so the problem
may well have been hidden by this slowness.
I've no idea what could cause this at this time; it doesn't seem to
be filesystem-related. ps shows both rsync processes waiting in select,
while netstat shows send and receive queues full on both sides.
ktrace shows this could be an issue with select(2):
  4102      1 rsync    1311780519.324063908 CALL  select(4,0x7f7fffff83b0,0x7f7f
ffff8390,0,0x7f7fffff83d0)
  4102      1 rsync    1311780579.483436279 RET   select 0
  4102      1 rsync    1311780579.483440327 CALL  select(4,0x7f7fffff83b0,0x7f7f
ffff8390,0,0x7f7fffff83d0)
  4102      1 rsync    1311780579.483442445 RET   select 1
  4102      1 rsync    1311780579.483443326 CALL  read(3,0x7f7ff7a36de2,0x21a)
  4102      1 rsync    1311780579.483451341 GIO   fd 3 read 538 bytes

Select blocks, and returns after the timeout period, while there is data
ready to be read. The next select call returns immediatly. Did something
change in this area recently ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--