poor pcie ssd driver performance on linux 2.6.18(centos 5.7)
I have a pcie driver for SSD which reaches a throughput of 3Gbytes/sec when working in centos 6.5(linux 2.6.32).
When I run the same driver under centos 5.7(linux 2.6.18) after performing some minor modifications I can only reach 400Mbytes/sec.
I am using the fio tool on the raw device in order to test performance.The driver uses the blk_queue_make _request function to regiter the bio handling function in order to override the linux elevator.
Can you please tell what could be the reason for the drop in performance?