Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH 3/3] WorkStruct: Use direct assignment rather than cmpxchg() | From | James Bottomley <> | Date | Thu, 07 Dec 2006 15:06:37 -0600 |
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On Thu, 2006-12-07 at 20:06 +0000, David Howells wrote: > Remember: if you have to put a conditional jump in there, it's going to fail > one way or the other a certain percentage of the time, and that's going to > cause a pipeline stall, and these ops are used quite a lot.
That we'd have to put a conditional jump in there is an incorrect assumption on risc machines. At least on parisc we can do conditional nullifies in the executing instruction pipeline, so we'd read, nullify the following write if the bit were set. We do this a lot in our page interruption handlers.
James
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