On 16 Aug 2024, at 18:12, Roger Heflin <rogerheflin@gmail.com> wrote:

So here is why sync sucks only on a usb 2.0 connection.

The report that lead to the revert of the sync change was on 3.0 connections.

The slow down was x10 or more.

So no this is not a USB 2 only issue.

Only if the user program and the USB device can overlap I/O do you get the max speed.

If the user space program has to wait on the previous write then you always see a dramatic slowdown.

Barry