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    SubjectRe: [RFC PATCH 4/4] [RESEND] Recomputing msgmni on memory add / remove
    Yasunori Goto wrote:
    >>Yasunori Goto wrote:
    >>>Hello Nadia-san.
    >>>>@@ -118,6 +122,10 @@ struct ipc_namespace {
    >>>> size_t shm_ctlall;
    >>>> int shm_ctlmni;
    >>>> int shm_tot;
    >>>>+ struct notifier_block ipc_memory_hotplug;
    >>>I'm sorry, but I don't see why each ipc namespace must have each callbacks
    >>>of memory hotplug.
    >>>I prefer only one callback for each subsystem, not for each namespace.
    >>>In addition, the recompute_msgmni() calculation looks very similar for
    >>>all ipc namespace.
    >>>Or do you wish each ipc namespace have different callback for the future?
    >>Actually, this is what I wanted to do at the very beginning: have a
    >>single callback that would recompute the msgmni for each ipc namespace.
    >>But the issue here is that the namespaces are not linked to each other,
    >>so I had no simple way to go through all the namespaces.
    >>I solved the issue by having a callback for any single ipc namespace and
    >>make it recompute the msgmni value for itslef.
    > The recompute_msg() must be called when new ipc_namespace is created/removed
    > as you mentioned. I think namespaces should be linked each other for it
    > in the end....

    Not if I do it the same way as for memory hotplug:
    1) definee a "namespace event notifier"
    2) insert another notifier block into the ipc namespace.
    3) The callback routines in the notifier chain would be activated upon
    namespace creation / removal.

    But I'm still thinking about it: Matt Helsley suggested that we might
    just copy the old namespace's value when creating a new namespace.

    There's also the issue of an msgmni that has been changed via procfs:
    may be we should not unconditionally recompute it upon namespace
    creation / removal, so unregister the callback for the owning namespace
    as soon as msgmni has been changed from userspace.


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      Last update: 2008-01-15 11:21    [W:0.036 / U:5.912 seconds]
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