netdev - Re: [PATCH net-next 3/3] tipc: reduce transmission rate of reset messages when link is down

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Message-ID: <57041AFA.5090702@cogentembedded.com>
Date:	Tue, 5 Apr 2016 23:07:22 +0300
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Jon Maloy <jon.maloy@...csson.com>, davem@...emloft.net
Cc:	netdev@...r.kernel.org,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	parthasarathy.bhuvaragan@...csson.com, richard.alpe@...csson.com,
	ying.xue@...driver.com, maloy@...jonn.com,
	tipc-discussion@...ts.sourceforge.net
Subject: Re: [PATCH net-next 3/3] tipc: reduce transmission rate of reset
 messages when link is down

Hello.

On 04/05/2016 07:20 PM, Jon Maloy wrote:

> When a link is down, it will continuously try to re-establish contact
> with the peer by sending out a RESET or and ACTIVATE message at each

    And/or?

> timeout interval. The default value for this interval is currently
> 375 ms. This is wasteful, and may become a problem in very large
> clusters with dozens or hundereds of nodes being down simultaneously.

    Hundreds.

> We now introduce a simple backoff algorithm for these cases. The
> first five messages are sent at default rate; thereafter a message
> is sent only each 16't timer interval.

    16th?

> This will cover the vast majority of link recyling cases, since the

    Recycling.

> endpoint starting last will transmit at the higher speed, and the link
> should normally be established well be before the rate needs to be
> reduced.
>
> The only case where we will see a degradation of link re-establishment
> is when the endpoins remain intact, and a glitch in the transmission

    Endpoints.

> media is causing the link reset. We will then experience a worst-case
> re-establishing time of 6 seconds, something we deem acceptable.
>
> Acked-by: Ying Xue <ying.xue@...driver.com>
> Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
[...]

MBR, Sergei