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    SubjectRe: [PATCH] cpumask: alloc blank cpumask left over
    Linus Torvalds wrote:
    > On Fri, 5 Jun 2009, Rusty Russell wrote:
    >> OK, here's what I've got in my tree. Ingo, I think this should go in the
    >> current -rc to avoid nasty bugs.
    > Why is the fix not to simply clear it in alloc?
    >> BTW, the original alloc_cpumask_var did zero; that was dropped after arguments
    >> over efficiency and fitting with other interfaces, but I clearly had the old
    >> semantics in my head for a while.
    > How could this ever be a efficiency issue? If you allocate cpumasks so
    > often that it's an efficiency problem, it would seem that you have bigger
    > issues than the memset. You'll have to initialize them some other way
    > anyway, so it's not like you can ever really avoid the dirty cachelines.
    > IOW, why isn't the fix just to clean up the horrible mess that is
    > alloc_cpumask_var_node() once and for all. Why not something like this?
    > The end result looks a lot simpler.
    > Or you could just add in that __GFP_ZERO there, and remove the memset. I
    > don't care. But the current code just looks messy and crazy, and that
    > FIXME is bogus. The end of the allocation needs to be cleared regardless.

    some alloc_cpumask_var or alloc_cpumask_var_node calling are followed by
    cpumask_copy etc to assign the allocated cpuamsk_var_t.

    about 66% calling are falling to that case.


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      Last update: 2009-06-05 19:51    [W:0.051 / U:2.272 seconds]
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