On Fri, 2009-03-13 at 10:23 +0000, Michael Meeks wrote: > > With the data=ordered setting in ext3 (the default), any fsync will > > result in all dirty data being flushed, not just the data in that file. > > This can be pretty expensive if there is a lot of outstanding I/O. > > Sure - on ext3 it's a 'sync()' call effectively, with the added bonus > that this has a terrible effect on other applications trying to use the > I/O subsystem to eg. read audio to play your mp3, or swap, or allocate > memory, or ... ;-) > > Calling 'fsync' regularly on ext3 will bring your system to a grinding > halt, quite regularly, cf. my comments on hair-loss etc. Lots of our > users will be on these systems, and last I checked [ did you poke your > kernel guys on this ? ] this was not recommended.
Ah, but the recommendations from the "kernel" people involved with ext4 is that "everything that cares about data" should call fsync: https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/54 And this is from the horses mouth. He wrote ext3... > > However, this is only a problem if such an operation happens often, and > > file saving is just not that common. > > Sure; although amusingly, if it happens often ~enough (say every few > hundred ms) - then we almost move the OS into a semi-synchronous writes > mode, and have somewhat less to write each time, and so don't suffer > multi-second glitches in the I/O subsystem ;-) Yes, but I'd say the problem here is that we shouldn't be saving every few hundred ms. Thats total crap on e.g. a SSD, and generally just a bad idea. > > It occurs often enought that there were several people in the ubuntu > > ext4-eats-my-data bug that had it happen to them multiple times. > > Nasty indeed, and this is the only solution. I suppose the nutshell of > my concern is this: > > * can we in some (evil or otherwise) way avoid hurting > desktop performance, interactivity and playback for > all ext2/3 systems, and still keep ext4 users happy ? :-) Another yucky thing is that statfs can't tell the difference between ext3 and ext4. They have the same magic number... > Of course, perhaps I'm just way off / out of date wrt. my dislike of > fsync, let me hunt down some kernely people for a sane 2nd opinion. Please do. _______________________________________________ gtk-devel-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/gtk-devel-list
