vsync problem with gles 2.0 code on Batocera 37-dev for RG35XX Beta v0.8

[reinholdPL]

Hi, I'm writing code using gles 2.0. for now it's just rotating triangle. My question is - is there some sort of vsync?
My fps are capped at stable value (~270 fps for single triangle), but even if I draw hundreds of same triangle fps count is still the same. At the same time cpu usage by my program is at ~3%. I tried using eglSwapInterval but to no avail.
Is there any way i can disable vsync, or at least someone could explain to me how it works?