Chris Mason <chris.mason@xxxxxxxxxx> writes: >> All three filesystems use the generic mpages code for reads, so they >> all get the same (bad) I/O patterns. Looks like we need to fix this up >> ASAP. > > Can you easily run btrfs through the same rig? We don't use mpages and > I'm curious. The readahead code was to blame, here. I wonder if we can change the logic there to not break larger I/Os down into smaller sized ones. Fengguang, doing a dd if=file of=/dev/null bs=1M results in 128K I/Os, when 128KB is the read_ahead_kb value. Is there any heuristic you could apply to not break larger I/Os up like this? Does that make sense? Cheers, Jeff -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
