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    SubjectRe: [PATCH 1/5] try parent numa_node at first before using default
    On Thu, 12 Jul 2007 07:47:52 +0200,
    Stefan Richter <> wrote:

    > The patch does nothing for all subsystems which do
    > device_initialize(&dev);
    > dev->parent = pd;
    > device_add(&dev);
    > Let's avoid to add infrastructure which does nothing, or only does
    > something by accident.

    I agree. dev->parent now is only expected to be set in device_add(),
    not in device_initialize(), so the sequence above is perfectly fine.
    (Why should you need it, anyway? parent information becomes necessary
    only when something is added to the tree.)
    > The alternatives are:
    > - Change all subsystems to set dev->parent before device_initialize().
    > *Document* that the device_initialize() API has this requirement.
    > This is counter-intuitive, amounts to some work across the kernel,
    > and could be gotten wrong again in future code because it's a
    > counter-intuitive API.

    Yes. We shouldn't do that.
    > - Move your code from device_initialize() to device_add(). One minor
    > drawback is that node-specific allocations based on the device's
    > numa_node would not be optimized before device_add(), but there is
    > probably no need for this. Driver probes come after device_add().

    I'd expect most allocations to be done when probing, so this shouldn't
    hurt much.
    > - Let subsystems explicitly call set_dev_node() on their own.
    > Also keep in mind that either device_move() should update the numa_node,
    > or the subsystems which call device_move() should explicitly update it
    > on their own. (Unless they know that their devices will always stay at
    > the same NUMA node even when switching parents.)

    I'd trust the subsystems to know best whether something regarding NUMA
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      Last update: 2007-07-12 09:17    [W:0.024 / U:5.240 seconds]
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