最近备份恢复Gogs的时候，发现同样的配置参数在Mac上访问Gogs的用户首页特别慢，大概耗时8秒，而在Linux上面运行的时候不到1秒钟。后来就上网搜索，加上自己试验，最后找到了原因应该是Gogs镜像本身的问题（可能是采用了alpine这一内核，但是具体原因不详，有待进一步实验）。
这个过程中曾经怀疑是Docker运行MySQL过慢的原因，虽然最终发现不是，但是搜索过程中发现了Docker for Mac确实有性能问题，那就是对大量磁盘IO的操作性能会非常差，大概会差10倍。
具体讨论可以看附录的帖子，这里大概摘录一下：
It seems the VM calls the virtio-blk implementation of flush in hyperkit approximately 25000 times. Each of these is implemented currently by an fsync(F_FULLFSYNC) to avoid writes being partially written or re-ordered over a power loss (as recommended by the Apple docs). Unfortunately each fsync(F_FULLFSYNC) seems to take about 10ms which accounts for the slowdown.
I agree that there are important use-cases where data persistence is less important than throughput, especially on developer setups or CI builds where containers are ephemeral. I’ll investigate the possibility of a configuration option.
解决办法
帖子里面也给出了解决办法，就是通过修改配置文件。以下方法适应于17.03.0-CE。
1$ cd ~/Library/Containers/com.docker.docker/Data/database/
2git reset --hard
3HEAD is now at 5e56922 last-start-time changed at 1487162086
4$ echo os > com.docker.driver.amd64-linux/disk/on-flush
5$ git add com.docker.driver.amd64-linux/disk/on-flush
6$ git commit -s -m 'Use fsync'
7[master d0b523f] Use fsync
8 1 file changed, 1 insertion(+), 1 deletion(-)