This is the source code repository for the paper entitled "Asynchronous I/O Stack: A Low-latency Kernel I/O Stack for Ultra-Low Latency SSDs" in the 2019 USENIX Annual Technical Conference

• Enable CONFIG_AIOS and CONFIG_INTEL_IOMMU (set to y).
• Enable CONFIG_NVME_CORE and CONFIG_BLK_DEV_NVME (set to y, not module).
• Open a file using a O_AIOS or 040000000 flag. The file should be located in Ext4 file system and in an NVMe SSD.
• Access the file using read(), pread(), write(), pwrite(), fsync() and fdatasync().

• The source code is not tested with SSDs having a volatile write cache. All tested NVMe SSDs have the non-volatile write cache feature.
• The current implementation supports only one NVMe SSD at a time. If you have multiple NVMe SSDs, the macro DEV_INSTANCE in drivers/nvme/host/pci.c should be properly adjusted to specify an NVMe SSD you want to apply AIOS to.
• The current implementation does not support the mmap() path.