Re: [patch] get_request starvation fix

[Andrew Morton <akpm@zip.com.au>]

Dieter Nützel wrote:
> 
> On Fri, Feb 08 2002, Andrew Morton wrote:
> > Here's a patch which addresses the get_request starvation problem.
> 
> [snip]
> 
> > Also, you noted the other day that a LILO run *never* terminated when
> > there was a dbench running.  This is in fact not due to request
> > starvation.  It's due to livelock in invalidate_bdev(), which is called
> > via ioctl(BLKFLSBUF) by LILO.  invalidate_bdev() will never terminate
> > as long as another task is generating locked buffers against the
> > device.
> [snip]
> 
> Could this below related?
> I get system looks through lilo (bzlilo) from time to time with all latest
> kernels + O(1) + -aa + preempt
> 

Depends what you mean by "system locks".  The invalidate_bdev() problem
won't lock the machine.  Its symptoms are merely that the ioctl will
not terminate until the process which is writing to disk stops.

In other words: if you run dbench, then lilo, lilo will not complete
until after dbench terminates.

If you're seeing actual have-to-hit-reset lockups then that'll
be due to something quite different.

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