  Using the Insight-HXMT observations of GRS 1915+105 when it exhibits low
frequency quasi-periodic oscillations (QPOs), we measure the evolution of the
QPO frequency along with disk inner radius and mass accretion rate. We find a
tight positive correlation between the QPO frequency and mass accretion rate.
Our results extend the finding of previous work with AstroSat to a larger range
of accretion rate with independent instruments and observations. Treating the
QPO frequency of GRS 1915+105 as the relativistic dynamic frequency of a
truncated disk, we are able to confirm the high spin nature of the black hole
in GRS 1915+105. We also address the potential of our finding to test general
relativity in the future.
