Messages in this thread | | | Subject | Re: Hyper-Threading Vulnerability | From | Arjan van de Ven <> | Date | Sat, 14 May 2005 21:48:46 +0200 |
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On Sat, 2005-05-14 at 15:21 -0400, Lee Revell wrote: > On Sat, 2005-05-14 at 20:01 +0200, Arjan van de Ven wrote: > > On Sat, 2005-05-14 at 13:56 -0400, Lee Revell wrote: > > > On Sat, 2005-05-14 at 18:44 +0200, Arjan van de Ven wrote: > > > > then JACK is terminally broken if it doesn't have a fallback for non- > > > > rdtsc cpus. > > > > > > It does have a fallback, but the selection is done at compile time. It > > > uses rdtsc for all x86 CPUs except pre-i586 SMP systems. > > > > > > Maybe we should check at runtime, > > > > it's probably a sign that JACK isn't used on SMP systems much, at least > > not on the bigger systems (like IBM's x440's) where the tsc *will* > > differ wildly between cpus... > > Correct. The only bug reports we have seen related to the use of the > TSC is due to CPU frequency scaling. The fix is to not use it - people > who want to use their PC as a DSP for audio probably don't want their > processor slowing down anyway.
it's a matter of time (my estimate is a year or two) before processors get variable frequencies based on temperature targets etc... and then rdtsc is really useless for this kind of thing..
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