Author: Robert Hyatt
Date: 10:10:59 10/30/02
Go up one level in this thread
On October 30, 2002 at 12:33:00, Eugene Nalimov wrote: >On October 30, 2002 at 10:53:58, Robert Hyatt wrote: > >>On October 30, 2002 at 06:59:21, Terje Vagle wrote: >> >>>Hi all, >>> >>>The new cpu from intel will have a new function called >>>hyper-threading. >>> >>>This will make the operating system able to recognize the cpu as if it was >>>2 cpu's. >>> >>>Could the programs with smp-support make use of this? >>> >>>Regards, >>> >>>Terje Vagle >> >> >>Yes, but it is going to cause some problems. You don't _really_ have two cpus. >>You >>have a single cpu executing two threads, and when one thread "blocks" waiting on >>a >>memory access or anything else (FP result) then the other thread will run. >> >>Spinlocks will wreck this however... > >There is special new instruction PAUSE for such a spinlocks. It is handled as >NOP on all existing (Intel and non-Intel) x86 CPUs prior to P4. It suspends a >(hyper)thread on P4 CPU for undisclosed amount of clock cycles. > >Thanks, >Eugene basically like sched_yield() does in the linux process scheduler? Simply tells the scheduler "if you got anything else to run, run it, otherwise come back to me and I'll continue."???
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