On Sat, 4 Aug 2007, Ingo Molnar wrote: > > yeah, it's really ugly. But otherwise i've got no real complaint about > ext3 - with the obligatory qualification that "noatime,nodiratime" in > /etc/fstab is a must.
I agree, we really should do something about atime. But the fsync thing is a real issue. It literally makes ext3 almost unusable from a latency standpoint on many loads. I have a fast disk, and don't actually tend to have all that much going on normally, and it still hurts occasionally. One of the most common (and *best*) reasons for using fsync is for the mail spool. So anybody that uses local email will actually be doing a lot of fsync, and while you could try to thread the interfaces, I don't think a lot of mailers do. So fsync ends up being a latency issue for something that a lot of people actually see, and something that you actually end up working with and you notice the latencies very clearly. Your editor auto-save feature is another good example of that exact same thing: the fsync actually is there for a very good reason, even if you apparently decided that you'd rather disable it. But yeah, "noatime,data=writeback" will quite likely be *quite* noticeable (with different effects for different loads), but almost nobody actually runs that way. I ended up using O_NOATIME for the individual object "open()" calls inside git, and it was an absolutely huge time-saver for the case of not having "noatime" in the mount options. Certainly more than your estimated 10% under some loads. The "relatime" thing that David mentioned might well be very useful, but it's probably even less used than "noatime" is. And sadly, I don't really see that changing (unless we were to actually change the defaults inside the kernel). Linus - 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/