From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
Nandita Dukkipati <nanditad@google.com>,
Neal Cardwell <ncardwell@google.com>,
Yuchung Cheng <ycheng@google.com>,
Sangtae Ha <sangtae.ha@gmail.com>
Subject: Re: [PATCH net-next 1/2] tcp_cubic: add SNMP counters to track how effective is Hystart
Date: Fri, 5 Dec 2014 01:17:54 +0100 [thread overview]
Message-ID: <20141205001754.GG16959@breakpoint.cc> (raw)
In-Reply-To: <1417738403.22424.28.camel@edumazet-glaptop2.roam.corp.google.com>
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> When deploying FQ pacing, one thing we noticed is that CUBIC Hystart
> triggers too soon.
>
> Having SNMP counters to have an idea of how often the various Hystart
> methods trigger is useful prior to any modifications.
>
> This patch adds SNMP counters tracking, how many time "ack train" or
> "Delay" based Hystart triggers, and cumulative sum of cwnd at the time
> Hystart decided to end SS (Slow Start)
>
> myhost:~# nstat -a | grep Hystart
> TcpExtTCPHystartTrainDetect 9 0.0
> TcpExtTCPHystartTrainCwnd 20650 0.0
> TcpExtTCPHystartDelayDetect 10 0.0
> TcpExtTCPHystartDelayCwnd 360 0.0
>
> ->
> Train detection was triggered 9 times, and average cwnd was
> 20650/9=2294,
> Delay detection was triggered 10 times and average cwnd was 36
Alternatively we could add INET_DIAG_CUBICINFO and export such info via ss
tool.
next prev parent reply other threads:[~2014-12-05 0:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-05 0:13 [PATCH net-next 1/2] tcp_cubic: add SNMP counters to track how effective is Hystart Eric Dumazet
2014-12-05 0:17 ` Florian Westphal [this message]
2014-12-05 1:10 ` Eric Dumazet
2014-12-05 0:55 ` Neal Cardwell
2014-12-09 19:58 ` David Miller
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