On Sat, 2007-08-04 at 17:48 -0400, Theodore Tso wrote: > On Sat, Aug 04, 2007 at 01:13:19PM -0700, Arjan van de Ven wrote: > > there is another trick possible (more involved though, Al will have to > > jump in on that one I suspect): Have 2 types of "dirty inode" states; > > one is the current dirty state (meaning the full range of ext3 > > transactions etc) and "lighter" state of "atime-dirty"; which will not > > do the background syncs or journal transactions (so if your machine > > crashes, you lose the atime update) but it does keep atime for most > > normal cases and keeps it standard compliant "except after a crash". > > That would make us standards compliant (POSIX explicitly says that > what happens after a unclean shutdown is Unspecified) and it would > make things a heck of a lot faster. However, there is a potential > problem which is that it will keep a large number of inodes pinned in > memory, which is its own problem. So there would have to be some way > to force the atime updates to be merged when under memory pressure, > and and perhaps on some much longer background interval (i.e., every > hour or so).
on the journalling side this would be one transaction (not 5 milion) and... since inodes are grouped on disk, you can even get some better coalescing this way... Wonder if we could do inode-grouping smartly; eg if we HAVE to write inode X, also write out the atime-dirty inodes in range X-Y to X+Y (where Y is some tunable) in the same IO.. -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org - 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/
