On Mon, May 11, 2015 at 09:24:09AM -0700, Sage Weil wrote: > > Let me re-ask the question that I asked last week (and was apparently > > ignored). Why not trying to use the lazytime feature instead of > > pointing a head straight at the application's --- and system > > administrators' --- heads? > > Sorry Ted, I thought I responded already. > > The goal is to avoid inode writeout entirely when we can, and > as I understand it lazytime will still force writeout before the inode > is dropped from the cache. In systems like Ceph in particular, the > IOs can be spread across lots of files, so simply deferring writeout > doesn't always help. Sure, but it would reduce the writeout by orders of magnitude. I can understand if you want to reduce it further, but it might be good enough for your purposes. I considered doing the equivalent of O_NOMTIME for our purposes at $WORK, and our use case is actually not that different from Ceph's (i.e., using a local disk file system to support a cluster file system), and lazytime was (a) something I figured was something I could upstream in good conscience, and (b) was more than good enough for us. Cheers, - Ted P.S. I do agree that if we do need this upstream, requiring a mount option to enable the feature is probably a good compromise. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
