jmeter - How can I set condition to execute some steps just for particular amount of users -

how can set condition in jmeter step 80% of users execute , 20% of users not. please me this. have http sampler , want execute 80% of users in test, when number of users (threads) change percentage of executed requests sampler stay same.

if have samplers want work in threads, not all, easiest way add them if controller , in condition add like:

${__random(1,100)} <= 80 

in case requests in controller has 80% chance run (fires when random lower or equal 80). of course it's not perfect, can go +-5% of requests it's fastest , easiest way know. , sort of randomness it's more real life experience.