Re: [PATCH] livelock in elevator scheduling

Jens Axboe
2000-12-02T16:14:10Z

On Fri, Dec 01 2000, Russell Cattelan wrote:
> > If performance is down, then that problem is most likely elsewhere.
> > I/O limited benchmarking typically thrives on lots of request
> > latency -- with that comes better throughput for individual threads.
> >
> > > Anyway, I'll try your patch.
>
> Well this patch does help with the request starvation problem.
> Unfortunately it has introduced another problem.
> Running 4 doio programs, on and XFS partion with KIO buf IO turned on.

This looks like a generic aic7xxx problem, and not block related. Since
you are doing such nice traces, what is the other CPU doing? CPU1
seems to be stuck grabbing the io_request_lock (for reasons not entirely
clear from reading the aic7xxx source...)

--
* Jens Axboe <axboe@suse.de>
* SuSE Labs