[formerly_proven]

> The modern linux kernel doesn't actually write to disk when fsync is called. It buffers the writes in a cache.

That's not true, you can tell in many ways but one of the easiest is because fsync is quite slow and noisy (on hard drives).

[Shorel]

I would be a bit disappointed if the kernel implementation for HDD and SSD is exactly the same.

[Unklejoe]

For a SATA SSD, I would be surprised if it was different.