On 11-03-06 11:06 AM, Calvin Walton wrote: > > There actually is such a periodic jump in overhead,
Ahh. So my instincts were correct. > caused by the way > which btrfs dynamically allocates space for metadata as needed by the > creation of new files, which it does whenever the free metadata space > ratio reaches a threshold (it's probably more complicated than that, but > close enough for now). Sounds fair enough. > To see exactly what's going on, you should use the "btrfs filesystem df" > command to see how space is being allocated for data and metadata > separately: > > ayu ~ # btrfs fi df / > Data: total=266.01GB, used=249.35GB > System, DUP: total=8.00MB, used=36.00KB > Metadata, DUP: total=3.62GB, used=1.93GB > ayu ~ # df -h / > Filesystem Size Used Avail Use% Mounted on > /dev/sda4 402G 254G 145G 64% / > > If you use the btrfs tool's df command to account for space in your > testing, you should get much more accurate results. Indeed! Unfortunately that tool seems to be completely silent on my system: # btrfs filesystem df /mnt/btrfs-test/ # btrfs filesystem df /mnt/btrfs-test Where /mnt/btrfs-test is where I have the device that I created the btrfs filesystem on mounted. i.e.: # grep btrfs /proc/mounts /dev/mapper/btrfs--test-btrfs--test /mnt/btrfs-test btrfs rw,relatime 0 0 My btrfs-tools appears to be from 20101101. The changelog says: * Merging upstream version 0.19+20101101. Cheers, b.
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