From: Eric Dumazet <[email protected]>
Date: Thu, 6 Dec 2018 09:58:24 -0800
> tcp_tso_should_defer() can return true in three different cases :
>
> 1) We are cwnd-limited
> 2) We are rwnd-limited
> 3) We are application limited.
>
> Neal pointed out that my recent fix went too far, since
> it assumed that if we were not in 1) case, we must be rwnd-limited
>
> Fix this by properly populating the is_cwnd_limited and
> is_rwnd_limited booleans.
>
> After this change, we can finally move the silly check for FIN
> flag only for the application-limited case.
>
> The same move for EOR bit will be handled in net-next,
> since commit 1c09f7d073b1 ("tcp: do not try to defer skbs
> with eor mark (MSG_EOR)") is scheduled for linux-4.21
>
> Tested by running 200 concurrent netperf -t TCP_RR -- -r 60000,100
> and checking none of them was rwnd_limited in the chrono_stat
> output from "ss -ti" command.
>
> Fixes: 41727549de3e ("tcp: Do not underestimate rwnd_limited")
> Signed-off-by: Eric Dumazet <[email protected]>
> Suggested-by: Neal Cardwell <[email protected]>
> Reviewed-by: Neal Cardwell <[email protected]>
> Acked-by: Soheil Hassas Yeganeh <[email protected]>
> Reviewed-by: Yuchung Cheng <[email protected]>
Applied.
