On 26 Oct 2015, at 22:58, Yuchung Cheng [off-list ref] wrote:

but would RDB be voided if this developer turns on RDB then turns on
Nagle later?

The short answer is answer is "kind of"

My understanding is that Nagle will delay segments until they're
either MSS-sized or until segments "down the pipe" are acknowledged.

As RDB isn't able to bundle if the payload is more than MSS/2, only
an application that that sends data less frequent than an RTT would
still theoretically benefit from RDB even if Nagle is on.

However, in my opinion this is a scenario where Nagle itself is void:

If you transmit more rarely than the RTT, enabling Nagle makes no
difference.

If you transfer more frequent than the RTT, enabling Nagle makes
RDB void.

-Jonas