Today, in Free Practice 2...

Today in Shanghai, during the second Free Practice session for the 2015 Chines GP...

A man ran across the track.



Kimi had problems with brakes,



Massa crashed, just a little,





Vettel found the limit of grip.



Mercedes were back in dominant form.



Check out the awesome interactive graphic from Giroveloce.it.   Y is time, X is lap,  you can deselect drivers by clicking on their name at the bottom.

While the author warns tire compound data may not be entirely correct (the F1 app, as usual, did not work properly)  you can get a sense of who managed to to do long runs and their relative pace.
Keep in mind there were interruptions due to the loony tunes crossing the track and Massa and Kvyat going off.

So Hamilton was able to to an 8 lap stint on options with a 1 second delta while Rosberg did 13 laps on primes with the same delta, start to finish.

In the Ferrari camp, looks like Vettel was not able to complete any long runs while Raikkonen was able to do 19 laps on primes.

Pos	Driver	Car	Time	Gap	Laps
1	Lewis Hamilton	Mercedes	1m37.219s	-	32
2	Kimi Raikkonen	Ferrari	1m37.662s	0.443s	35
3	Daniel Ricciardo	Red Bull/Renault	1m38.311s	1.092s	24
4	Sebastian Vettel	Ferrari	1m38.339s	1.120s	30
5	Nico Rosberg	Mercedes	1m38.399s	1.180s	35
6	Daniil Kvyat	Red Bull/Renault	1m38.737s	1.518s	10
7	Valtteri Bottas	Williams/Mercedes	1m38.850s	1.631s	27
8	Felipe Nasr	Sauber/Ferrari	1m39.032s	1.813s	26
9	Romain Grosjean	Lotus/Mercedes	1m39.142s	1.923s	32
10	Jenson Button	McLaren/Honda	1m39.275s	2.056s	29
11	Pastor Maldonado	Lotus/Mercedes	1m39.444s	2.225s	30
12	Fernando Alonso	McLaren/Honda	1m39.743s	2.524s	27
13	Marcus Ericsson	Sauber/Ferrari	1m39.751s	2.532s	33
14	Max Verstappen	Toro Rosso/Renault	1m39.894s	2.675s	32
15	Carlos Sainz	Toro Rosso/Renault	1m39.971s	2.752s	28
16	Nico Hulkenberg	Force India/Mercedes	1m40.151s	2.932s	28
17	Felipe Massa	Williams/Mercedes	1m40.423s	3.204s	7
18	Sergio Perez	Force India/Mercedes	1m40.868s	3.649s	24
19	Roberto Merhi	Marussia/Ferrari	1m42.973s	5.754s	27
20	Will Stevens	Marussia/Ferrari	1m44.564s	7.345s	8