[RC5] Pentium4: Benchmark and real keyrate are different

Mark Renfer mri at netsec.ch
Wed Sep 26 15:54:56 EDT 2001

Howdy folks,

Has anyone of you noticed that the RC5 keyrate reported by the benchmark
code on a P4 is actually about 20% higher than the real speed that the
will be cracking at? I can reproduce this on several P4 machines running W2K
with both the latest client as well as an older client. I have reinstalled
the OS on
one machine which didn't change the behaviour. Raising the client's priority
doesn't help either. The P4 has hardware features that allows the processor
reduce it's own clock speed to prevent it from overheating if not properly
I have checked that this is not the problem by watching the CPU temperature
as well as the current clock speed using the Intel utility. The processors
well below their specifications regarding temperatur and the Intel utility
indicate that the processors reduce their speed. So I am pretty sure that
this is not an issue of this kind. I can run the benchmark over and over
which drives the processors to the same temperatur as they go when running
the client, but still the keyrate reported by the benchmark is 20% higher.
I get ~2MKeys on 1.7GHz machines while the benchmark reports ~2.5MKeys.
In the speed database of DNet the P4/1.7 has 5 records all 2.4+ MKeys.
I wonder if there is actually something wrong with my machines or if the
benchmark reports a wrong keyrate. This could be the case even when taking
into account the entries in the speed database since the people reporting
the keyrates probably used the benchmark feature to get the numbers.

Also, does anybody know of any work regarding an optimized core for the
P4 using SSE2?

Kind regards,       Mark

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