Direct cached reads slow - nvme

Direct cached reads slow - nvme

[jackwolf2454]

[-- Attachment #1: Type: text/plain, Size: 829 bytes --]

linux 4.17.0
btrfs-progs v4.16.1

Label: none  uuid:
        Total devices 1 FS bytes used 128.00KiB
        devid    1 size 465.63GiB used 20.00MiB path /dev/nvme0n1p3


before mkfs.brtfs


/dev/nvme0n1p3:
 Timing O_DIRECT cached reads:   6112 MB in  2.00 seconds = 3056.19 MB/sec
 Timing O_DIRECT disk reads: 9138 MB in  3.00 seconds = 3045.73 MB/sec



after creating mkfs.btrfs /dev/nvme0n1p3

/dev/nvme0n1p3:
 Timing O_DIRECT cached reads:   2558 MB in  2.00 seconds = 1278.52 MB/sec
 Timing O_DIRECT disk reads: 9148 MB in  3.00 seconds = 3049.05 MB/sec



after creating mkfs.ext4 /dev/nvme0n1p3

/dev/nvme0n1p3:
 Timing O_DIRECT cached reads:   2102 MB in  2.00 seconds = 1050.20 MB/sec
 Timing O_DIRECT disk reads: 9194 MB in  3.00 seconds = 3064.60 MB/sec



Is this behaviour normal?

[-- Attachment #2: pEpkey.asc --]
[-- Type: application/pgp-keys, Size: 1795 bytes --]