In this paper, we attempt to manage GC overhead at the operating system level. In our approach, first, we use a machine learning technique to devise a GC detecting mechanism at the operating system level, and second, we show that by making use of this mechanism performance variance normally observed on SSDs can be reduced. We develop a GC-detector that detects garbage collection of SSDs and request TRIM operations to the SSD when GC is detected. Experimental results running the GC-detector show increase average bandwidth and low performance variance compared to when not using GC-detector.