Changing the Sampling Rate
The sampling rate is the average ratio of the number of packets incoming on an sFlow-enabled port, to the number of flow samples taken from those packets.
You can change the default (global) sampling rate. You also can change the rate on an individual port, overriding the default sampling rate of 512. With a sampling rate of 512, on average, one in every 512 packets forwarded on an interface is sampled.