On Thu, Jul 14, 2005 at 06:46:23PM -0600, Scott Long wrote: ... > How often are you going to be changing the scheduler at runtime? Is in general, almost never. However, suppose you have per-device schedulers as phk was suggesting, then you'd really like to decouple the devices so reconfiguring one of them does not affect the others. Anyways there might be a way out... requests go from dev_strategy() to the individual disksort routine where, during the switch, the scheduler can 'absorb' them while the real queue drains (assuming the subsequent device_start() routine does not complain too much for finding the queue empty!). Then, when the device queue becomes empty (the scheduler knows because it is serving the bio_remove() requests) it can switch to the new one, and resubmit old requests through dev_strategy(). This would also solve the problem of implementing non-work-conserving schedulers. Basically it's the same approach followed in dummynet, you steal the packets from ip_{input,output}() and resubmit them later. Does any of you know what are the assumptions (locks held etc.) for calling dev_strategy() in 5.x and above ? cheers luigi > the scheduler meant to be aware of individual devices? Again, I'm > not advocating that the upper layers be able to look at or manipulate > the driver bioq's. > > Scott > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"Received on Thu Jul 14 2005 - 23:13:57 UTC
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