On Fri, 3 Apr 2009, Theodore Ts'o wrote: > > Please pull from: > > git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git ext3-latency-fixes Thanks, pulled. I'll be interested to see how it feels. Will report back after I've rebuild and gone through a few more emails. One thing I started wondering about in your changes to start using WRITE_SYNC is that I'm getting closer to thinking that we did the whole WRITE-vs-WRITE_SYNC thing the wrong way around. Now, it's clearly true that non-synchronous writes are hopefully always the common case, so in that sense it makes sense to think of "WRITE" as the default non-critical case, and then make the (fewer) WRITE_SYNC cases be the special case. But at the same time, I now suspect that we could actually have solved this problem more easily by just doing things the other way around: make the default "WRITE" be the high-priority one (to match "READ"), and then just explicitly marking the data writes with "WRITE_ASYNC". Why? Because I think that with all the writes sprinkled around in random places, it's probably _easier_ to find the bulk writes that cause the biggest issues, and just fix _those_ to be WRITE_ASYNC. They may be bulk, they may be the common case, but they also tend to be the case where we write with generic routines (eg the whole "do_writepages()" thing). So the VFS layer tends to already do much of the bulk writeout, and maybe we would have been better off just changing those to ASYNC and leaving any more specialized cases as the SYNC case? That would have avoided a lot of this effort at the filesystem level. We'd just assume that the default filesystem-specific writes tend to all be SYNC. Comments? Linus -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
