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    SubjectRe: [RFC PATCH 0/6] Convert all tasklets to workqueues
    On Mon, 25 Jun 2007 18:50:03 +0200
    Tilman Schmidt <tilman@imap.cc> wrote:

    > Ingo Molnar <mingo@elte.hu> wrote:
    > > so how about the following, different approach: anyone who has a tasklet
    > > in any performance-sensitive codepath, please yell now.


    Getting rid of tasklet's may seem like a good idea. But doing it by changing
    them all to workqueue's would have bad consequences for networking.

    The first issue is that it would change the semantic assumptions in the
    places where tasklets are used. Many places "know" that a tasklet runs in soft
    irq context so extra locking is not needed.

    The performance overhead of changing to workqueue's could also be disastrous for
    some devices. There are 10G device drivers that use tasklets to handle transmit
    completion.


    Here is a more detailed list how network devices are using tasklet's

    Receive packet handling: ifb, ppp, ipw2200, ipw2100
    Receive buffer refill: acenic, s2io
    Receive & Transmit: sc9031, sundance
    Transmit buffer allocation: smc91x
    Phy handling: skge

    Sorry, if you are going to get rid of tasklets, you need to fix all the
    network drivers first.

    --
    Stephen Hemminger <shemminger@linux-foundation.org>
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