On Mon, 16 Nov 2015, Renju Liu wrote: > Hi All, > > I'm currently studying the PM system in Linux 3.10. Before the kernel > starts suspension, it needs to sync filesystem to the disk by calling > sys_sync(). It doesn't _need_ to do this. As you realized, the data will be retained okay even if it isn't written out to the disk. The system does this just for safety, even though it isn't needed. > Anyone knows the reason? Because the suspension will only power > off the CPU but will the memory power on, and hence the file buffer's > information won't get lost even if the system is suspended (assume the > system does not go to hibernate). Thanks. Think about what will happen if the battery drains completely while the system is suspended. Alan Stern
