On Tue, 2006-07-04 at 10:09 +0200, Andi Kleen wrote:
> On Tuesday 04 July 2006 09:51, 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) ?
>
> Where do you see an atomic operation?
test_tsk_thread_flag() ends up doing an atomic op afaics
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