set axis tick labels in TikZ

xtick={50000,60000,70000,80000,90000,100000,110000,120000,130000,140000}, at axis options

http://tex.stackexchange.com/questions/46793/axis-tick-numbers-overlap-in-tikz

e.g.


\begin{axis}[
height=2in,
width=3in,
xmin=0,
ymin=0,
xlabel={Packet Size / KB},
ylabel={Time / million CPU cycles},
xtick={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16},
ytick={20,40,60,80,100,120},
font=\small,
title={},
legend style={at={(0,0)}, anchor=south west}
]