lkml.org 
[lkml]   [2007]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 1/5] try parent numa_node at first before using default
    On Thu, 12 Jul 2007 07:47:52 +0200,
    Stefan Richter <stefanr@s5r6.in-berlin.de> 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
    changed.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-07-12 09:17    [W:0.022 / U:29.972 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site