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From: Fan Du <fengyuleidian0615@gmail.com>
To: John Heffner <johnwheffner@gmail.com>
Cc: Fan Du <fan.du@intel.com>, Eric Dumazet <edumazet@google.com>,
	David Miller <davem@davemloft.net>,
	Netdev <netdev@vger.kernel.org>
Subject: Re: [PATCHv4 net-next 2/3] ipv4: Use binary search to choose tcp PMTU probe_size
Date: Thu, 05 Mar 2015 10:36:54 +0800	[thread overview]
Message-ID: <54F7C146.603@gmail.com> (raw)
In-Reply-To: <CABrhC0kTmdv7TJUFo88HjGgzLmm1p4_XRnuQZUoaOGh8DwmhVw@mail.gmail.com>

于 2015年03月04日 21:39, John Heffner 写道:
>> >I suspect there's plenty of room for further improvement in the
>> >probing heuristic, but this seems like a reasonable improvement.
>> >
>> >Acked-by: John Heffner<johnwheffner@gmail.com>
> Actually, one final suggestion here.  The cost of a failed probe is
> much higher than a successful probe.  I'd suggest still bounding the
> probe segment size to no more than 2*cur_mss.  (Think of a common case
> where mss_clamp = 9000 - headers, but the actual path MTU = 1500.)

huh...
Are you serious about clamping probe size to no more than 2*current_mss?
What about the opposite scenario where path MTU enlarges, e.g., current_mss
is nearing search_low?

I will make next version incorporating:
a. Update ip-sysctl.txt
b. Zero probe_size before reset search_low/high


>    -John

  reply	other threads:[~2015-03-05  2:41 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-03  9:19 [PATCHv4 net-next 0/3] Improvements for TCP PMTU Fan Du
2015-03-03  9:19 ` [PATCHv4 net-next 1/3] ipv4: Raise tcp PMTU probe mss base size Fan Du
2015-03-03 16:52   ` John Heffner
2015-03-03  9:19 ` [PATCHv4 net-next 2/3] ipv4: Use binary search to choose tcp PMTU probe_size Fan Du
2015-03-03 16:51   ` John Heffner
2015-03-04 13:39     ` John Heffner
2015-03-05  2:36       ` Fan Du [this message]
2015-03-03  9:19 ` [PATCHv4 net-next 3/3] ipv4: Create probe timer for tcp PMTU as per RFC4821 Fan Du
2015-03-03 16:39   ` John Heffner
2015-03-04  2:11     ` Fan Du
2015-03-04 13:26       ` John Heffner
2015-03-05  2:36         ` Fan Du
2015-03-03 16:43 ` [PATCHv4 net-next 0/3] Improvements for TCP PMTU John Heffner
2015-03-04  2:12   ` Fan Du

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