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SubjectRe: elevator-starvation-4 (2.2.14 && 2.3.42)
Hi,

On Fri, 11 Feb 2000 06:26:32 -0800, Bruce Thompson
<bruce@otherother.com> said:

> It isn't terribly surprising to me that the problem seems to
> develop more with IDE than SCSI: Time spent generating requests for
> an IDE device is time that the driver cannot service those requests
> since the CPU must actively work to service the requests.

It looks as if that doesn't have anything to do with the situation here
--- the IDE drivers use the default elevator queuing, whereas the SCSI
drivers take the requests off the elevator queue immediately and then do
their own queuing within the SCSI layers. The difference in the two
queuing policies appears to be what is dominating the performance
differences between the two, as fixing IDE's queuing does give us a very
much fairer request response curve.

--Stephen

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