Messages in this thread | | | Subject | Re: Hyper-Threading Vulnerability | From | Alan Cox <> | Date | Sat, 14 May 2005 16:23:10 +0100 |
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On Sad, 2005-05-14 at 00:38, Lee Revell wrote: > Well yes but you would still have to recompile those apps. And take the > big performance hit from using gettimeofday vs rdtsc. Disabling HT by > default looks pretty good by comparison.
You cannot use rdtsc for anything but rough instruction timing. The timers for different processors run at different speeds on some SMP systems, the timer rates vary as processors change clock rate nowdays. Rdtsc may also jump dramatically on a suspend/resume.
If the app uses rdtsc then generally speaking its terminally broken. The only exception is some profiling tools.
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