Hans van Kranenburg - 19.09.18, 19:58: > However, as soon as we remount the filesystem with space_cache=v2 - > > > writes drop to just around 3-10 MB/s to each disk. If we remount to > > space_cache - lots of writes, system unresponsive. Again remount to > > space_cache=v2 - low writes, system responsive. > > > > That's a huuge, 10x overhead! Is it expected? Especially that > > space_cache=v1 is still the default mount option? > > Yes, that does not surprise me. > > https://events.static.linuxfound.org/sites/events/files/slides/vault20 > 16_0.pdf > > Free space cache v1 is the default because of issues with btrfs-progs, > not because it's unwise to use the kernel code. I can totally > recommend using it. The linked presentation above gives some good > background information.
What issues in btrfs-progs are that? I am wondering whether to switch to freespace tree v2. Would it provide benefit for a regular / and /home filesystems as dual SSD BTRFS RAID-1 on a laptop? Thanks, -- Martin
