暂定一个位置
HDD 测试

+-----------+-----------+----------+-----------+----------+
| Test Item | 读取 IOPS | 读取速度 | 写入 IOPS | 写入速度 |
+-----------+-----------+----------+-----------+----------+
| Seq-Q32T1 |      4621 | 577 MB/s |      1304 | 163 MB/s |
| Seq       |       245 | 245 MB/s |        98 |  98 MB/s |
| 4K-Q32T1  |      1266 |   4 MB/s |       386 |   1 MB/s |
| 4K        |       171 | 685 KB/s |       121 | 487 KB/s |
+-----------+-----------+----------+-----------+----------+

writeback模式

echo writeback > /sys/class/block/bcache0/bcache/cache_mode

+-----------+-----------+----------+-----------+----------+
| Test Item | 读取 IOPS | 读取速度 | 写入 IOPS | 写入速度 |
+-----------+-----------+----------+-----------+----------+
| Seq-Q32T1 |      1820 | 227 MB/s |      1836 | 229 MB/s |
| Seq       |       164 | 164 MB/s |       228 | 228 MB/s |
| 4K-Q32T1  |       621 |   2 MB/s |    102480 | 400 MB/s |
| 4K        |       179 | 718 KB/s |     40876 | 159 MB/s |
+-----------+-----------+----------+-----------+----------+

nvme 缓存之后
关闭sequence_cutoff

echo 0 > /sys/class/block/bcache0/bcache/sequential_cutoff

+-----------+-----------+-----------+-----------+-----------+
| Test Item | 读取 IOPS |  读取速度 | 写入 IOPS |  写入速度 |
+-----------+-----------+-----------+-----------+-----------+
| Seq-Q32T1 |      5207 |  650 MB/s |     25206 | 3.08 GB/s |
| Seq       |      1539 | 1.50 GB/s |      2618 | 2.56 GB/s |
| 4K-Q32T1  |    174297 |  680 MB/s |     91101 |  355 MB/s |
| 4K        |     21170 |   82 MB/s |     39506 |  154 MB/s |
+-----------+-----------+-----------+-----------+-----------+

4K读写性能提升效果之大不用多说，看数据就知道