Optimize librbd for Lower CPU Cost and Higher Scalability - Li Wang, DiDi This talk will introduce our work to reduce CPU overhead of qemu+librbd stack, which includes use rbd_aio_writev instead of rbd_aio_write for qemu rbd driver, and further optimize rbd_aio_writev to use zero copy to send data, these optimizations lead to 48% less cpu cost, 46% less latency, and 85% higher iops for 1M sequential write. In addition, we improve the scalability of librbd by using multiple writeback threads, and reduce the granularity of rbd cache lock. About Li Wang Senior Technical Expert, DiDi Li Wang is a senior technical expert in DiDi.