On 12/21/19 1:24 AM, Chris Murphy wrote:
Hi,
Recent kernels, I think since 5.1 or 5.2, but tested today on 5.3.18,
5.4.5, 5.5.0rc2, takes quite a long time for `fstrim /` to complete,
just over 1 minute.
Filesystem Size Used Avail Use% Mounted on
/dev/nvme0n1p7 178G 16G 161G 9% /
fstrim stops on this for pretty much the entire time:
ioctl(3, FITRIM, {start=0, len=0xffffffffffffffff, minlen=0}) = 0
top shows the fstrim process itself isn't consuming much CPU, about
2-3%. Top five items in per top, not much more revealing.
Samples: 220K of event 'cycles', 4000 Hz, Event count (approx.):
3463316966 lost: 0/0 drop: 0/0
Overhead Shared Object Symbol
1.62% [kernel] [k] find_next_zero_bit
1.59% perf [.] 0x00000000002ae063
1.52% [kernel] [k] psi_task_change
1.41% [kernel] [k] update_blocked_averages
1.33% [unknown] [.] 0000000000000000
On a different system, with older Samsung 840 SATA SSD, and a fresh
Btrfs, I can't reproduce. It takes less than 1s. Not sure how to get
more information.
You want to try Dennis's async discard stuff? That should fix these problems
for you, the patches are in Dave's tree. Thanks,
Josef
