[Bug 9729] ondemand cpufreq governor doesn't see when kcryptd/dm-crypt is busy

[bugme-daemon@bugzilla.kernel.org]

http://bugzilla.kernel.org/show_bug.cgi?id=9729


tch@wpkg.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |REJECTED
         Resolution|                            |INVALID




------- Comment #3 from tch@wpkg.org  2008-01-18 14:42 -------
This indeed must be some kind of dm-crypt/kcryptd "feature" and/or some
confusion on how to read CPU usage.

While reading from that dm-crypt device, the following CPU usage was shown (the
numbers are consistent across a few tests):

187 MHz -> ~75% system CPU time in top
375 MHz -> ~66% system CPU time in top
562 MHz -> ~94% system CPU time in top
750 MHz -> ~85% system CPU time in top
937 MHz -> ~85% system CPU time in top
1125 MHz -> ~83% system CPU time in top
1312 MHz -> ~70% system CPU time in top
1500 MHz -> ~70% system CPU time in top


Looks like dm-crypt won't eat the whole CPU power for some reason.

With default 80 as up_threshold for "ondemand" governor, no wonder the
frequency didn't scale up.

So a "fix" for this bug is a matter of lowering up_threshold.


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