Applications Power Management

Device IOs are Expensive

Hard disk, CDs, and analog moving parts consume a lot of power when in use. High speed links (SATA, PCIe, etc.) consume lot of power, as well, unless they are in power savings mode. Applications have to be aware of any actions that can result in device IOS and try to avoid them when possible. Applications should also be aware of non-obvious actions that can result in device IOs. For example, opening a file that is in cache can still result in device IO to update ATIME. Use of O_NOATIME flag will avoid this IO.