On 2019/1/14 下午7:47, Tomasz Chmielewski wrote: >> When rebasing my qgroup + balance optimization patches, I found one very >> obvious performance regression for balance. >> >> For normal 4G subvolume, 16 snapshots, balance workload, v4.20 kernel >> only takes 3s to relocate a metadata block group, while for v5.0-rc1, I >> don't really know how it will take as it hasn't finished yet. > > Are you sure it's v5.0-rc1 regression, not earlier? At least for what I'm describing, yes. v5.0-rc1 introduced bug, and already pinned down. So I'm afraid you're hitting another different bug. > > I'm trying to do a metadata-only balance from RAID-5 to RAID-1, with > 4.19.8. > > It was going relatively "normal", until it got stuck and showing no > progress. > > I've canceled the balance, upgraded to 4.20, started the balance again.> For straight 11 days, it rewrote terabytes of data on the disks, with no > progress at all.> Also, 4.19.8 had a balance interrupted because of "out > of space", despite we have terabytes free. > > Metadata RAID-5 usage stays at 4.12GiB for the past 11 days (and a few > more days with 4.19.8). Are you using qgroup? Which is another huge cause of slow balance. Thanks, Qu > > > > # btrfs fi usage /data > WARNING: RAID56 detected, not implemented > WARNING: RAID56 detected, not implemented > Overall: > Device size: 14.47TiB > Device allocated: 112.06GiB > Device unallocated: 14.36TiB > Device missing: 0.00B > Used: 107.93GiB > Free (estimated): 0.00B (min: 8.00EiB) > Data ratio: 0.00 > Metadata ratio: 1.64 > Global reserve: 512.00MiB (used: 1.86MiB) > > Data,RAID5: Size:5.28TiB, Used:3.04TiB > /dev/sda5 1.76TiB > /dev/sdb5 1.76TiB > /dev/sdc5 1.76TiB > /dev/sdd5 1.76TiB > > Metadata,RAID1: Size:56.00GiB, Used:53.97GiB > /dev/sda5 29.00GiB > /dev/sdb5 27.00GiB > /dev/sdc5 27.00GiB > /dev/sdd5 29.00GiB > > Metadata,RAID5: Size:12.38GiB, Used:11.13GiB > /dev/sda5 4.12GiB > /dev/sdb5 4.12GiB > /dev/sdc5 4.12GiB > /dev/sdd5 4.12GiB > > System,RAID1: Size:32.00MiB, Used:416.00KiB > /dev/sdb5 32.00MiB > /dev/sdc5 32.00MiB > > Unallocated: > /dev/sda5 1.83TiB > /dev/sdb5 1.83TiB > /dev/sdc5 1.83TiB > /dev/sdd5 1.83TiB > > > # btrfs balance status /data > Balance on '/data' is running > 13 out of about 64 chunks balanced (15 considered), 80% left
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