Scheduler fixes for hyperthreading

Marcel Moolenaar marcel at
Sun May 22 01:19:42 PDT 2005

On May 21, 2005, at 9:35 PM, Colin Percival wrote:

> Marcel Moolenaar wrote:
>> There are a lot of variables that need to be taken into account and
>> those variables do not necessarily map perfectly from a P4 to an I2.
>> Sharing of the L1 cache is not a sufficient condition to create a
>> side-channel for timing attacks. A reliable time source with enough
>> precision is also necessary (as you and Stephan have pointed out).
>> The precision of the time source depends on latencies of the various
>> cache levels and the micro-architectural behavior of the processor.
> Point taken.  I maintain, however, that it is much better to make
> "information can leak between these processors" a machine-independent
> concept which is handled appropriately by the scheduler (with the
> necessary machine-dependent code to specify *which* sets of processors,
> if any, have such leakage).

Yes, I agree. I forgot to explicitly acknowledge that point in my
previous emails. Sorry about that...

  Marcel Moolenaar         USPA: A-39004          marcel at

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