netdev - Re: ping6 packets high probability loss occurs by the default firewalld rule(rpfilter invert) with low traffic generated by iperf

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Message-ID: <7c9c80df-66fa-7383-7b5b-b300de8b6485@huawei.com>
Date:   Fri, 15 Nov 2019 11:57:34 +0800
From:   hujunwei <hujunwei4@...wei.com>
To:     David Ahern <dsahern@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>, <davem@...emloft.net>,
        <kafai@...com>, <weiwan@...gle.com>
CC:     <netdev@...r.kernel.org>, <wangxiaogang3@...wei.com>,
        <xuhanbing@...wei.com>
Subject: Re: ping6 packets high probability loss occurs by the default
 firewalld rule(rpfilter invert) with low traffic generated by iperf



On 2019/11/14 23:39, David Ahern wrote:
>>>>
>>>
>>> perhaps it is time to update IPv6's gc_thresh to match IPv4's - meaning
>>> it stays but gets set to -1 and is not used. Is there a reason to keep a
>>> limit these days?
>>>
>> I think it is unnecessary to keep this limit, because the default gc_thresh will result in ipv6 packet loss in low ipv6 traffic.
>> There are two solutions:
>> 1) Why not check the percpu route first in ip6_pol_route_lookup() when rt6_find_cached_rt() retrun NULL, just like ip6_pol_route(). Can anyone help to answer this?
> 
> AIUI it's different for no specific reason - just a different lookup
> written for different use cases.
> 
> ip6_route_lookup for example (which is what netfilter code is using)
> does not even need an rt6_info, it just wants to know the lookup is good
> and check the egress device. Meaning, all it really needs is the
> fib6_info from the lookup under rcu. That (or helper to validate the
> lookup and device) is the right long term solution, but a much bigger
> change that I have time for right now.
> 
Hi David,
Thank you so much for the reply, so when will you update it?
I really look forward to your patch.

Regards Junwei