On Thursday, 5 July 2007 14:38, Nigel Cunningham wrote: > Hi. > > On Thursday 05 July 2007 22:25:06 Rafael J. Wysocki wrote: > > On Thursday, 5 July 2007 01:45, Pavel Machek wrote: > > > On Tue 2007-07-03 21:32:20, Oliver Neukum wrote: > > > > Am Dienstag, 3. Juli 2007 schrieb Miklos Szeredi: > > > > > > And a further question. The freezer is not atomic. What do you do > > > > > > if a task not yet frozen calls sys_sync(), but fuse is already > frozen? > > > > > > > > > > What do you do if a task not yet frozen writes to a pipe, on the other > > > > > end of which is a task already frozen? > > > > > > There's some difference between uninterruptible and interruptible > > > sleep I'd say. > > > > > > > > It doesn't matter. The only thing that should matter during suspend > > > > > (not hibernate) is saving the state of devices to ram, and putting the > > > > > devices to sleep. > > > > > > > > Well, but you did remove sys_sync() from the freezer, which is > > > > and must be called in the hibernate path. > > > > > > Not "must". In fact, hibernation should be safe without sys_sync(). It > > > is just user un-friendly. > > > > In fact, I'd like to remove the sys_sync() from the freezer entirely, > because > > it just doesn't belong in there. > > > > The only advantege of having sys_sync() in freeze_processes() is that we > > have a chance to write out everything when applications cannot produce more > > data to write, but there are filesystems which don't do that anyway (eg. > XFS), > > so generally there's no reason to bother. > > Shouldn't XFS - and fuse - be considered to be broken? Sync should sync data > and if XFS isn't doing that, it's wrong. > > In the case of fuse, we should have a mechanism by which fuse processes can be > made to sync if they do have any pending I/O, and by which they can be frozen > later than other userspace processes. > > I'd like to see the sync stay, because it improves reliability and data > integrity in the fail-to-resume case. Calling scripts would probably invoke > sync themselves if they don't already, but that's racy. As it is at the > moment, we know userspace is stopped, so syncing isn't racy. I'd like to move the sync out of the freezer, but to call it from the suspend/hibernation code, so that we do sys_sync(); error = freeze_processes(); etc. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
