Re: Kernel 2.6.6 & 2.6.7 sometime hang after much I/O

[Matthias Schniedermeyer <ms@citd.de>]

On Sun, Jun 20, 2004 at 11:05:23PM +1000, Nick Piggin wrote:
> Matthias Schniedermeyer wrote:
> 
> >Here we go.
> >
> >Addendum: After some time more and more konsole froze. Up to the point
> >where i (had to) kill(ed) X(CTRL-ALT-Backspace) and after i couldn't
> >even log in at the console anymore i rebooted (into 2.6.5). Then i
> >recompiled 2.6.7 with SYSRQ-support and tried to reproduce the hanging
> >without X. After 3 runs i "gave up" and started X. Here i had luck and
> >the process ('cut-movie.pl') froze at first try. Then i killed X and did
> >the above on the console.
> >
> >As the system is currently unsuable enough to reboot, i will reboot in
> >2.6.5 after this mail, but i can always reboot into 2.6.7 if you need
> >more input.
> >
> >
> 
> The attached trace was with 2.6.7, right?

Yes.

> Can you reproduce the hang, then, as root, do:
> 
> 	echo 1024 > /sys/block/sda/queue/nr_requests
> 
> Replace sda with whatever devices your hung processes were
> doing IO to. Do things start up again?

1 try (with X) with unchanged nr_requests. (I was stupid enough to issues the
command on the wrong HDD :-) )
(AFAIR i had the same situation with 2.6.6, sometimes the hang didn't happen)

6 tries (with X) with nr_requests=1024 and no hang.

1 try with nr_requests back to 128 and now it hangs.
now changing to nr_request=1024 doesn't seem to change anyting, my
konsoles start to freeze.


Don't know if it is relevant but the bytes transfered are always rougly
around 3000-3400MB (1500-1700 MB read & 1500-1700 MB write. The program
reads 100MB, then writes 100MB, then issues "sync", the hangs happend
always about every after 15-17 "rounds")





Bis denn

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