ALMOST. The limit is indeed 'compensation' or the fixed amount, whichever is less.

For self-employment, the deductible 'employer half' of SE tax that is subtracted is actually 8000 * .9235 * (.124+.029)/2 = 565 as computed in schedule SE part I, giving 8000 - 565 = 7435. But this doesn't matter, because the fixed limit of 6000 + 1000 = 7000 is lower either way. (Thanks glglgl)

The fixed limit is adjusted for inflation, but only in steps of $500. It was 5500 from 2013 through 2018, so it probably won't move up again for a while.