How much data were you writing? If you don't fill the OS's page cache and the SSD controller's DRAM cache, and you're not blocking on fsync() or O_DIRECT or som

How much data were you writing? If you don't fill the OS's page cache and the SSD controller's DRAM cache, and you're not blocking on fsync() or O_DIRECT or some other explicit flushing mechanism, then you're not going to see much of a difference in throughput.