Re: blk_congestion_wait racy?

[Andrew Morton]

Martin Schwidefsky <schwidefsky@xxxxxxxxxx> wrote:
>
> > An ouch-per-second sounds reasonable.  It could simply be that the CPUs
> > were off running other tasks - those timeout are less than scheduling
> > quanta.
> 
> I don't understand why an ouch-per-second is reasonable. The mempig is
> the only process that runs on the machine and the blk_congestion_wait
> uses HZ/10 as timeout value. I'd expect about 100 ouches for the 10
> seconds the test runs.

blk_congestion_wait() is supposed to be terminated by someone releasing a
disk write request.  If no write requests are freed in 100 milliseconds
then either Something Is Up or that process simply was not scheduled for
some time after the wakeup was delivered.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/