Messages in this thread | | | Date | Thu, 17 Dec 2009 15:06:06 -0500 (EST) | From | Alan Stern <> | Subject | Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems) |
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On Thu, 17 Dec 2009, Rafael J. Wysocki wrote:
> That actually is correct. On the nx6325 suspend is totally dominated by disk > spindown, almost everything else is negligible compared to it (well, except for > the audio), so we can't go down below 1 s during suspend on this box. > > On the Wind, disk spindown time is comparable with serio suspend time, > so at least in principle we should be able to get .5 s suspend on this box - > if the disk spindown in async. > > In turn, the resume on the Wind is dominated by disk spinup, so we can't > go below 1.5 s on this box during resume (notice that the "async+extra" > approach brings us close to this limit, although we could save .5 s more in > principle by making more devices async). > > Resume on the nx6325 is a different story, though, as it is dominated by USB > and PCI devices, so marking those as async would probably bring us close to > the limit.
The implications seem pretty clear. If the following sorts of devices were async:
USB (devices and interfaces), PCI, serio, SCSI (hosts, targets, devices)
then we would reap close to the maximum benefit -- providing:
async threads are started in a first pass without waiting for synchronous devices, and
It's not clear that making all these types of devices async will really work, but it's worth testing.
Alan Stern
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