Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH 1/2] x86-64 TIF flags for debug regs and io bitmap in ctxsw | Date | Tue, 4 Jul 2006 10:09:31 +0200 |
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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?
Also on x86-64 unlikely is an no-op.
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