I'm playing with mining ETH and the client written in C. The output shows I'm mining at 10.3 Mh/s and I contribute to the Suprnova pool. The pool says I mine at 16Mh/s and goes up to 27Mh/s. I can't figure out if Suprnova is wrong (when I mined other currencies in the past it seemed accurate) or if the client is under reporting. How do you guys determine your real hash speed?
Pools calculate your hashrate based on number of submitted shares, as they never trust clients =)
The problem is ethereum miner works unstable with easy shares, so all the pools use a difficult shares. Often it is a static difficulty.
You can try to mine on nanopool.org - it shows both hashrates: reported and calculated, as well as number of accepted shares.