From: Stephen Hemminger <stephen@networkplumber.org>
To: Neal Cardwell <ncardwell@google.com>
Cc: David Miller <davem@davemloft.net>,
Netdev <netdev@vger.kernel.org>,
Yuchung Cheng <ycheng@google.com>,
Soheil Hassas Yeganeh <soheil@google.com>
Subject: Re: [PATCH net 1/5] tcp_bbr: cut pacing rate only if filled pipe
Date: Fri, 14 Jul 2017 16:15:35 -0700 [thread overview]
Message-ID: <20170714161535.66c5110a@xeon-e3> (raw)
In-Reply-To: <CADVnQykrv=U=jXa2SeOun8yGZbYJ4zoLvek-_GEo7sN02PsZLg@mail.gmail.com>
On Fri, 14 Jul 2017 18:54:02 -0400
Neal Cardwell <ncardwell@google.com> wrote:
> On Fri, Jul 14, 2017 at 6:36 PM, Stephen Hemminger
> <stephen@networkplumber.org> wrote:
> > On Fri, 14 Jul 2017 17:49:21 -0400
> > Neal Cardwell <ncardwell@google.com> wrote:
> >
> >> In bbr_set_pacing_rate(), which decides whether to cut the pacing
> >> rate, there was some code that considered exiting STARTUP to be
> >> equivalent to the notion of filling the pipe (i.e.,
> >> bbr_full_bw_reached()). Specifically, as the code was structured,
> >> exiting STARTUP and going into PROBE_RTT could cause us to cut the
> >> pacing rate down to something silly and low, based on whatever
> >> bandwidth samples we've had so far, when it's possible that all of
> >> them have been small app-limited bandwidth samples that are not
> >> representative of the bandwidth available in the path. (The code was
> >> correct at the time it was written, but the state machine changed
> >> without this spot being adjusted correspondingly.)
> >>
> >> Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control")
> >> Signed-off-by: Neal Cardwell <ncardwell@google.com>
> >> Signed-off-by: Yuchung Cheng <ycheng@google.com>
> >> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
> >
You are correct, these look more like bug fixes. I was a little concerned
that the changes would be visible but they really aren't user visible.
Should they go to stable as well?
next prev parent reply other threads:[~2017-07-14 23:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-14 21:49 [PATCH net 1/5] tcp_bbr: cut pacing rate only if filled pipe Neal Cardwell
2017-07-14 21:49 ` [PATCH net 2/5] tcp_bbr: introduce bbr_bw_to_pacing_rate() helper Neal Cardwell
2017-07-14 21:49 ` [PATCH net 3/5] tcp_bbr: introduce bbr_init_pacing_rate_from_rtt() helper Neal Cardwell
2017-07-14 21:49 ` [PATCH net 4/5] tcp_bbr: remove sk_pacing_rate=0 transient during init Neal Cardwell
2017-07-14 21:49 ` [PATCH net 5/5] tcp_bbr: init pacing rate on first RTT sample Neal Cardwell
2017-07-14 22:36 ` [PATCH net 1/5] tcp_bbr: cut pacing rate only if filled pipe Stephen Hemminger
2017-07-14 22:54 ` Neal Cardwell
2017-07-14 23:15 ` Stephen Hemminger [this message]
2017-07-15 0:29 ` Neal Cardwell
2017-07-15 21:44 ` David Miller
2017-07-16 5:18 ` Neal Cardwell
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