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Remember Cyrix and HLT?
Remember Cyrix and HLT?
Posted May 11, 2008 10:56 UTC (Sun) by kleptog (subscriber, #1183)Parent article: Matthew Garrett on the race to idle
Way back when I had a Cyrix chip and one nice thing about it was that when the OS did a HLT in the idle loop (which linux did at the time) the power usage dropped significantly. Which was good since these chips had a nasty habit of overheating when you tried to do anything complex. Is this something they did and no-one ever followed up on? Because it seemed to me like a rather obvious idea that everyone would do, but it seems I'm wrong... Seems rather a lot easier than switching sleep states several times per second.
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Remember Cyrix and HLT?
Posted May 11, 2008 14:36 UTC (Sun) by mjg59 (subscriber, #23239) [Link]
C states are effectively a more advanced implementation of the hlt instruction. C1 is equivalent to hlt, with deeper states disabling more of the CPU and introducing more latency.