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    SubjectRe: [linux-pm] [PATCH 0/8] Suspend block api (version 8)
    On Thu, May 27, 2010 at 07:59:02PM +0200, Thomas Gleixner wrote:
    > On Thu, 27 May 2010, Matthew Garrett wrote:
    > > ACPI provides no guarantees about what level of hardware functionality
    > > remains during S3. You don't have any useful ability to determine which
    > > events will generate wakeups. And from a purely practical point of view,
    > > since the latency is in the range of seconds, you'll never have a low
    > > enough wakeup rate to hit it.
    > Right, it does not as of today. So we cannot use that on x86
    > hardware. Fine. That does not prevent us to implement it for
    > architectures which can do it. And if x86 comes to the point where it
    > can handle it as well we're going to use it. Where is the problem ? If
    > x86 cannot guarantee the wakeup sources it's not going to be used for
    > such devices. The kernel just does not provide the service for it, so
    > what ?

    We were talking about PCs. Suspend-as-c-state is already implemented for

    > So the only thing you are imposing to app writers is to use an
    > interface which solves nothing and does not save you any power at
    > all.

    It's already been demonstrated that the Android approach saves power.

    > Runnable tasks and QoS guarantees are the indicators whether you can
    > go to opportunistic suspend or not. Everything else is just window
    > dressing.

    As I keep saying, this is all much less interesting if you don't care
    about handling suboptimal applications. If you do care about them then
    the Android approach works. Nobody has demonstrated a scheduler-based
    one that does.

    Matthew Garrett |

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