On macOS on the 16" MBP:
pg_test_fsync
5 seconds per test
Direct I/O is not supported on this platform.
Compare file sync methods using one 8kB write:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 27492.613 ops/sec 36 usecs/op
fdatasync 26373.551 ops/sec 38 usecs/op
fsync 26449.921 ops/sec 38 usecs/op
fsync_writethrough 41.503 ops/sec 24095 usecs/op
open_sync 27028.415 ops/sec 37 usecs/op
Compare file sync methods using two 8kB writes:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 12833.442 ops/sec 78 usecs/op
fdatasync 22520.738 ops/sec 44 usecs/op
fsync 22718.435 ops/sec 44 usecs/op
fsync_writethrough 39.467 ops/sec 25338 usecs/op
open_sync 12263.507 ops/sec 82 usecs/op
Compare open_sync with different write sizes:
(This is designed to compare the cost of writing 16kB in different write
open_sync sizes.)
1 * 16kB open_sync write 24691.753 ops/sec 40 usecs/op
2 * 8kB open_sync writes 12787.775 ops/sec 78 usecs/op
4 * 4kB open_sync writes 6507.818 ops/sec 154 usecs/op
8 * 2kB open_sync writes 3205.598 ops/sec 312 usecs/op
16 * 1kB open_sync writes 1617.759 ops/sec 618 usecs/op
Test if fsync on non-write file descriptor is honored:
(If the times are similar, fsync() can sync data written on a different
descriptor.)
write, fsync, close 9988.357 ops/sec 100 usecs/op
write, close, fsync 18553.995 ops/sec 54 usecs/op
Non-sync'ed 8kB writes:
write 26806.255 ops/sec 37 usecs/op
On Linux:
/usr/lib/postgresql/12/bin/pg_test_fsync -127-
5 seconds per test
O_DIRECT supported on this platform for open_datasync and open_sync.
Compare file sync methods using one 8kB write:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 568.044 ops/sec 1760 usecs/op
fdatasync 1307.635 ops/sec 765 usecs/op
fsync 710.051 ops/sec 1408 usecs/op
fsync_writethrough n/a
open_sync 718.734 ops/sec 1391 usecs/op
Compare file sync methods using two 8kB writes:
(in wal_sync_method preference order, except fdatasync is Linux's default)
open_datasync 283.945 ops/sec 3522 usecs/op
fdatasync 1108.933 ops/sec 902 usecs/op
fsync 640.977 ops/sec 1560 usecs/op
fsync_writethrough n/a
open_sync 357.980 ops/sec 2793 usecs/op
Compare open_sync with different write sizes:
(This is designed to compare the cost of writing 16kB in different write
open_sync sizes.)
1 * 16kB open_sync write 645.170 ops/sec 1550 usecs/op
2 * 8kB open_sync writes 356.379 ops/sec 2806 usecs/op
4 * 4kB open_sync writes 188.997 ops/sec 5291 usecs/op
8 * 2kB open_sync writes 88.864 ops/sec 11253 usecs/op
16 * 1kB open_sync writes 44.061 ops/sec 22696 usecs/op
Test if fsync on non-write file descriptor is honored:
(If the times are similar, fsync() can sync data written on a different
descriptor.)
write, fsync, close 714.729 ops/sec 1399 usecs/op
write, close, fsync 709.597 ops/sec 1409 usecs/op
Non-sync'ed 8kB writes:
write 814553.097 ops/sec 1 usecs/op
https://askubuntu.com/questions/87035/how-to-check-hard-disk-performance
Sequential READ speed with big blocks:
fio --name TEST --eta-newline=5s --filename=fio-tempfile.dat --rw=read --size=500m --io_size=10g --blocksize=1024k --ioengine=libaio --fsync=10000 --iodepth=32 --direct=1 --numjobs=1 --runtime=60 --group_reporting
Sequential WRITE speed with big blocks:
fio --name TEST --eta-newline=5s --filename=fio-tempfile.dat --rw=write --size=500m --io_size=10g --blocksize=1024k --ioengine=libaio --fsync=10000 --iodepth=32 --direct=1 --numjobs=1 --runtime=60 --group_reporting
Random 4K read QD1:
fio --name TEST --eta-newline=5s --filename=fio-tempfile.dat --rw=randread --size=500m --io_size=10g --blocksize=4k --ioengine=libaio --fsync=1 --iodepth=1 --direct=1 --numjobs=1 --runtime=60 --group_reporting
Mixed random 4K read and write QD1 with sync:
fio --name TEST --eta-newline=5s --filename=fio-tempfile.dat --rw=randrw --size=500m --io_size=10g --blocksize=4k --ioengine=libaio --fsync=1 --iodepth=1 --direct=1 --numjobs=1 --runtime=60 --group_reporting
Sequential READ:
READ: bw=3409MiB/s (3574MB/s), 3409MiB/s-3409MiB/s (3574MB/s-3574MB/s), io=10.0GiB (10.7GB), run=3004-3004msec
Sequential WRITE:
WRITE: bw=3126MiB/s (3278MB/s), 3126MiB/s-3126MiB/s (3278MB/s-3278MB/s), io=10.0GiB (10.7GB), run=3276-3276msec
Random 4k read QD1:
READ: bw=54.8MiB/s (57.4MB/s), 54.8MiB/s-54.8MiB/s (57.4MB/s-57.4MB/s), io=3287MiB (3447MB), run=60001-60001msec
Mixed random 4k read and write QD1 with fsync:
READ: bw=1074KiB/s (1100kB/s), 1074KiB/s-1074KiB/s (1100kB/s-1100kB/s), io=62.9MiB (65.0MB), run=60002-60002msec
WRITE: bw=1071KiB/s (1096kB/s), 1071KiB/s-1071KiB/s (1096kB/s-1096kB/s), io=62.7MiB (65.8MB), run=60002-60002msec
(Requires sudo and --ioengine=posixaio in the fio commands above)
Sequential READ:
READ: bw=3232MiB/s (3389MB/s), 3232MiB/s-3232MiB/s (3389MB/s-3389MB/s), io=10.0GiB (10.7GB), run=3168-3168msec
Sequential WRITE:
WRITE: bw=3174MiB/s (3328MB/s), 3174MiB/s-3174MiB/s (3328MB/s-3328MB/s), io=10.0GiB (10.7GB), run=3226-3226msec
Random 4k read QD1:
READ: bw=29.2MiB/s (30.6MB/s), 29.2MiB/s-29.2MiB/s (30.6MB/s-30.6MB/s), io=1753MiB (1838MB), run=60001-60001msec
Mixed random 4k read and write QD1 with fsync:
Run status group 0 (all jobs):
READ: bw=14.2MiB/s (14.9MB/s), 14.2MiB/s-14.2MiB/s (14.9MB/s-14.9MB/s), io=852MiB (894MB), run=60001-60001msec
WRITE: bw=14.1MiB/s (14.8MB/s), 14.1MiB/s-14.1MiB/s (14.8MB/s-14.8MB/s), io=848MiB (889MB), run=60001-60001msec