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    SubjectRe: Stop using tasklets for bottom halves
    On Mon, 7 Sep 2009 15:58:50 -0700
    "Luis R. Rodriguez" <> wrote:

    > A while ago I had read about an effort to consider removing tasklets
    > [1] or at least trying to not use them. I'm unaware of the progress in
    > this respect but since reading that article have always tried to
    > evaluate whether or not we need tasklets on wireless drivers. I have
    > also wondered whether work in irq context in other parts of the kernel
    > can be moved to process context, a curious example being timers. I'll
    > personally be trying to using only process context on bottom halves on
    > future drivers but I figured it may be a good time to ask how serious
    > was avoiding tasklets or using wrappers in the future to avoid irq
    > context is or is it advised. Do we have a general agreement this is a
    > good step forward to take? Has anyone made tests or changes on a
    > specific driver from irq context to process context and proven there
    > are no significant advantages of using irq context where you would
    > have expected it?
    > Wireless in particular should IMHO not require taskets for anything
    > time sensitive that I can think about except perhaps changing channels
    > quickly and to do that appropriately also process pending RX frames
    > prior to a switch. It remains to be seen experimentally whether or not
    > using a workqueue for RX processing would affect the time to switch
    > channels negatively but I doubt it would be significant. I hope to
    > test that with ath9k_htc.
    > What about gigabit or 10 Gigabit Ethernet drivers ? Do they face any
    > challenges which would yet need to be proven would not face issues
    > when processing bottom halves in process context?
    > [1]
    > Luis
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    Why not use NAPI, which is soft irq? Almost all 1G and 10G drivers
    use NAPI.

    Process context is too slow.


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