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    SubjectRe: [PATCH 1/2] x86-64 TIF flags for debug regs and io bitmap in ctxsw
    Arjan,

    On Tue, Jul 04, 2006 at 09:51:49AM +0200, Arjan van de Ven wrote:
    > > - }
    > > - }
    > > + if (unlikely((task_thread_info(next_p)->flags & _TIF_WORK_CTXSW))
    > > + || test_tsk_thread_flag(prev_p, TIF_IO_BITMAP))
    > > + __switch_to_xtra(prev_p, next_p, tss);
    >
    > well isn't this replacing an if() (which isn't cheap but also not
    > expensive, due to unlikely()) with an atomic operation (which *is*
    > expensive) ?
    >
    Andi is right. I double checked the test_tsk_thread_flag() and it does not
    use atomic ops.

    --
    -Stephane
    -
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