[perf] System S4 hibernate suspend time is longer than required

[Zhao Fan]

Bug detailed description:
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Image: Created on 12/17/2007
This bug is to track system S4 suspend performance issue. The requirement defines that "Time from user pressing sleep button to platform going to S4 state (not just display going blank) <= 10 sec", right now we need 21sec even if system is idle with nothing played.

Reproduce steps:
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1. ume-hibernate to S4 suspend the system, and record the time

Current result:
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The S4 hibernate suspend time is longer than required

Expected result:
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1. S4 hibernate suspend time should be less than 10s per defined.

Basic root-causing log:
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[rob rhoads (rob-rhoads)]

Martin: What is the current amount of time to save an image to disk and going into S4 state?

[martin (martin-xu)]

Currtly, we need more than 17s to suspend to S4.
the hibernate time depend on the work load, if we have a big image to save it will cause a long time.

Frankly to say it is not very easy to shorten the hibernate time within 10s. even thohough we have some creative and good idea to shorten the time, it is also very difficult to push it into kernel.

Fan:
we just use the bug to track the gap. I do not think it should be high. I suggest to set it to medium

[Zhao Fan (fan-zhao)]

In M11 testing, the suspend time has downgraded to about 30s.

[Zhao Fan (fan-zhao)]

Will not fix it for moblin1.0