On Mon, 2017-10-23 at 12:26 +0900, Koichiro Den wrote: > Now I wonder this is more of a theoretical one rather than a patch to fix one > specific bug.
Note that I said that your patch was fine and I added a 'Reviewed-by:' tag. What I meant is that it has no direct effect on correctness of TCP stack. I could not cook a packetdrill test that shows the difference before and after your patch. BTW, in the following sequence : A) Fetch high-res timestamp and store in X B) Use X B) Can use a quite old value of X, depending on scheduling (preempt kernels or interrupt handling) TCP really does not care of how accurate X is, it is a best effort. For RTX packets, it is even more the case, since TCP does not take RTT samples from packets that were retransmitted.
