From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: vvs@parallels.com, netdev@vger.kernel.org, kuznet@parallels.com,
jhs@mojatatu.com
Subject: Re: [PATCH 1/1] cbq: incorrect processing of high limits
Date: Tue, 02 Apr 2013 14:30:54 -0400 (EDT) [thread overview]
Message-ID: <20130402.143054.1460998027326004295.davem@davemloft.net> (raw)
In-Reply-To: <1364833476.5113.157.camel@edumazet-glaptop>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 01 Apr 2013 09:24:36 -0700
> On Mon, 2013-04-01 at 17:01 +0400, Vasily Averin wrote:
>> currently cbq works incorrectly for limits > 10% real link bandwidth,
>> and practically does not work for limits > 50% real link bandwidth.
>> Below are results of experiments taken on 1 Gbit link
>>
>> In shaper | Actual Result
>> -----------+---------------
>> 100M | 108 Mbps
>> 200M | 244 Mbps
>> 300M | 412 Mbps
>> 500M | 893 Mbps
>>
>> This happen because of q->now changes incorrectly in cbq_dequeue():
>> when it is called before real end of packet transmitting,
>> L2T is greater than real time delay, q_now gets an extra boost
>> but never compensate it.
>>
>> To fix this problem we prevent change of q->now until its synchronization
>> with real time.
>>
>> Signed-off-by: Vasily Averin <vvs@openvz.org>
>> Reviewed-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
...
> Acked-by: Eric Dumazet <edumazet@google.com>
Applied, thanks.
prev parent reply other threads:[~2013-04-02 18:30 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-01 13:01 [PATCH 1/1] cbq: incorrect processing of high limits Vasily Averin
2013-04-01 16:24 ` Eric Dumazet
2013-04-02 18:30 ` David Miller [this message]
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