On Fri, 27 Apr 2007, Nigel Cunningham wrote: > User input doesn't account for all system activity. Think of cron jobs > or user initiated jobs that may have started before the cycle began.
Yes, but the _user_ did not start them so they didn't lose any work. See, it might or might not be important but that's something the _userspace_ has much more knowledge than the kernel ever will. On Fri, 27 Apr 2007, Nigel Cunningham wrote: > Noooo! If the user looses data, the user will be concerned and we should > be. I for one would do my best to avoid using software that loses my > data for me. I wouldn't care if you said "Well, it's your fault. You > lost the data." From my perspective as a user, I didn't lose the data, > some part of the computer's OS did. You are looking at snapshot/shutdown from kernel and user experience point of view at the same time which causes confusion here. Let me repeat: it is _absolutely no concern_ of the _kernel_ whether you resume to a snapshot that does not contain all your precious data. The kernel doesn't care one bit! That being said, the _userspace solution_ obviously needs to take this into account by blocking user input, making filesystems read-only, and maybe even blocking certain background processes (cron and beagle indexing come into mind). On Fri, 27 Apr 2007, Nigel Cunningham wrote: > Sorry, but I just don't believe filesystems should need to throw away > metadata post resume. If we let data be changed after snapshotting (or > ourselves cause it to be changed), we're the ones that are broken. Our > snapshot is out of date and the expectations of userspace programs that > were snapshotted will be out of date. Just imagine, for example, a > userspace program that is snapshotted, then reads and deletes a > temporary file. After the snapshot restore, it's running again. But > wait, we can't read or delete the file again because it's already gone. > Life just gets more complicated and confusing this way. It doesn't. We can either make the filesystem read-only or, surprise, surprise, make a _snapshot_ of the filesystem! And while the points you raised are important for the full end-user solution, it is absolutely not interesting to snapshot_system(). The only thing it needs to guarantee is a consistent snapshot that we can resume later. On Fri, 27 Apr 2007, Nigel Cunningham wrote: > Maybe, but I'd still rather be encouraging! You are. Perhaps you just don't know it yet. ;-) Pekka - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/