  We report on recent results of the longitudinal double-spin asymmetry A_LL
from the STAR and PHENIX experiments. Data were collected in longitudinally
polarized proton-proton collisions at a center-of-mass energy of 200 GeV. The
results added new constraints to the polarized gluon distribution function g(x)
with the probed x range of 0:02 < x < 0:3. The results lead to the importance
of probing small x.
