Venkatesh Pallipadi wrote:
On Mon, Jun 13, 2011 at 3:06 PM, Jarod Wilson<jarod@xxxxxxxxxx> wrote:
TSC is high enough resolution that we can use its low-order byte to
stir new data into the random number generator entropy pool.
From what I vaguely remember from years past, rdtsc, especially last
few bits of it are not very good as random number source. As they are
based on lower bus frequency and a multiplier. May be things have
changed these days. Adding Peter and Suresh for comments.
Ah, that would definitely be good to know. I *have* enabled debug spew
on my primary test rig though, and the randomness appears to be quite
good in the low byte using tsc as the primary clocksource. Its a ~3+
year old core 2 duo 2.67GHz system though, so things could easily be
better or worse with more current systems, and I can't say that I've
tried it out exhaustively with the cpu at full-bore, which could affect
things (system is mostly idle, so acpi-cpufreq had the cpu dialed back).
--
Jarod Wilson
jarod@xxxxxxxxxx
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