On Tue, Feb 25, 2014 at 1:22 AM, Eric Dumazet [off-list ref] wrote:

From: Eric Dumazet <edumazet@google.com>

Upcoming congestion controls for TCP require usec resolution for RTT
estimations. Millisecond resolution is simply not enough these days.

FQ/pacing in DC environments also require this change for finer control
and removal of bimodal behavior due to the current hack in
tcp_update_pacing_rate() for 'small rtt'

...

---
v6: Do not use ktime_get() but skb_mstamp, as Stephen Hemminger pointed
    out some platforms have slow ktime_get()

...

 17 files changed, 174 insertions(+), 169 deletions(-)

I think it is safe, because we made sure (sack_rtt_us >= 0) is true.

Sounds good. Thanks, Eric!

Acked-by: Neal Cardwell <ncardwell@google.com>

neal