On 29/08/17 23:03, Dave Chinner wrote: > On Tue, Aug 29, 2017 at 09:23:10AM -0700, Christoph Hellwig wrote: >> On Tue, Aug 29, 2017 at 09:03:08AM -0700, Darrick J. Wong wrote: >>> First, should we land the incore extent map rework (not that I've seen a >>> patchset yet) so that the increased extent map fragmentation resulting >>> from cow/dedupe don't overwhelm the memory allocator with high order >>> allocations? Incore extent map memory usage hasn't been an issue here... >> >> Working on this now, but so far this hasn't been a major issue. >> The main workload where the extent list currently hurts and that >> prompted my work in this area doesn't even involve reflinks (sparse >> VM image). > > Yup, that's a problem, and it's going to be even more of a problem > once people start using reflink to snapshot sparse VM images. I > think that the extent rework is probably the most important thing we > need to solve for COW to be generally usable. Assuming I was feeling brave, what should I be doing to limit the chances of hitting this issue? Would smaller filesystems or lots of memory on the host help etc? Also what should I be monitoring to warn me before anything actually breaks? Thanks for the help so far. Chris -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
