Re: Blocked processes <=> Elevator starvation?

[Jens Axboe <axboe@suse.de>]

On Sun, Oct 29 2000, Miles Lane wrote:
> >> There were still some stalls but they only lasted a couple of
> >> seconds. The patch did make a difference and for the better.
> > 
> > 
> > Ok, still needs a bit of work. Thanks for the feedback.
> 
> Have you resolved this problem completely, now?
> 
> I am testing the USB Storage support with my ORB backup
> drive.  When I run:
> 
> 	dd if=/dev/zero of=/dev/sda bs=1k count=2G
> 
> The drive gets data quickly for about thirty seconds.
> Then the throughput drops off to about ten percent
> of its previous transfer rate.  This dropoff appears to
> be due to conflict over accessing filesystems.  Specifically,
> I have USB_STORAGE_DEBUG enabled, which shoots a ton of
> debugging output into my kernel log.  When the throughput
> to the ORB drive falls off, all writing to the syslog
> ceases.  At least, that's what "tail -f" shows.
> 
> I would be happy to test any patches you have for this
> problem.

Could you send vmstat 1 info from the start of the copy
and until the i/o rate drops off?

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