How can try CPU mining, just as a benchmark of CPU performance?

I don’t care about profitability even in the least.
I just want to try CPU mining as a benchmark.
I compiled bfgminer with CPU mining enabled (via ./configure parameters) however when I try to run it with this feature, pressing the M and + keys, bfgminer is unable to find the CPU as a mining device.
Then I compiled cgminer, and its minerd seems unable to even talk with bitcoin-qt.
Any ideas?