Messages in this thread | | | Subject | Re: Question on handling managed IRQs when hotplugging CPUs | From | Hannes Reinecke <> | Date | Tue, 5 Feb 2019 16:10:47 +0100 |
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On 2/5/19 3:52 PM, Keith Busch wrote: > On Tue, Feb 05, 2019 at 05:24:11AM -0800, John Garry wrote: >> On 04/02/2019 07:12, Hannes Reinecke wrote: >> >> Hi Hannes, >> >>> >>> So, as the user then has to wait for the system to declars 'ready for >>> CPU remove', why can't we just disable the SQ and wait for all I/O to >>> complete? >>> We can make it more fine-grained by just waiting on all outstanding I/O >>> on that SQ to complete, but waiting for all I/O should be good as an >>> initial try. >>> With that we wouldn't need to fiddle with driver internals, and could >>> make it pretty generic. >> >> I don't fully understand this idea - specifically, at which layer would >> we be waiting for all the IO to complete? > > Whichever layer dispatched the IO to a CPU specific context should > be the one to wait for its completion. That should be blk-mq for most > block drivers. > Indeed. But we don't provide any mechanisms for that ATM, right?
Maybe this would be a topic fit for LSF/MM?
Cheers,
Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.com +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
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