netdev - Re: UDP sockets oddities

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Message-ID: <ce4af8cc-3de1-a777-967c-a57103994e1d@gmail.com>
Date:   Fri, 25 Aug 2017 18:17:34 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     netdev@...r.kernel.org, edumazet@...il.com, pabeni@...hat.com,
        willemb@...gle.com, davem@...emloft.net
Subject: Re: UDP sockets oddities

On 08/25/2017 04:57 PM, Eric Dumazet wrote:
> On Fri, 2017-08-25 at 16:18 -0700, Florian Fainelli wrote:
> 
>> Eric, are there areas of the stack where we are allowed to drop packets,
>> not propagate that back to write(2) and also not increment any counter
>> either, or maybe I am not looking where I should...
> 
> What happens if you increase these sysctls ?

I don't see packet loss after I tweak these two sysctls according to
your suggestions.

Tweaking eth0's sysctls did not change anything, but tweaking gphy's
sysctl resolved the loss. This was a little surprising considering that
gphy is an IFF_NO_QUEUE interface and eth0 is the conduit interface that
does the real transmission.

Does that make sense with respect to what I reported earlier? Should I
try to dump the neigh stats?

Thanks!

> 
> grep .  `find /proc/sys|grep unres_qlen`
> 
> 
> unres_qlen_bytes -> 2000000
> unres_qlen -> 10000
> 
> 

-- 
Florian