netdev - Re: Huge memory leak with 4.15.0-rc2+

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Date:   Mon, 11 Dec 2017 23:27:52 +0100
From:   Paweł Staszewski <pstaszewski@...are.pl>
To:     John Fastabend <john.fastabend@...il.com>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: Huge memory leak with 4.15.0-rc2+



W dniu 2017-12-11 o 23:15, John Fastabend pisze:
> On 12/11/2017 01:48 PM, Paweł Staszewski wrote:
>>
>> W dniu 2017-12-11 o 22:23, Paweł Staszewski pisze:
>>> Hi
>>>
>>>
>>> I just upgraded some testing host to 4.15.0-rc2+ kernel
>>>
>>> And after some time of traffic processing - when traffic on all ports
>>> reach about 3Mpps - memleak started.
>>>
>
> [...]
>
>>> Some observations - when i disable tso on all cards there is more
>>> memleak.
>>>
>>>
>>>
>>>
>>>
>> When traffic starts to drop - there is less and less memleak
>> below link to memory usage graph:
>> https://ibb.co/hU97kG
>>
>> And there is rising slab_unrecl - Amount of unreclaimable memory used
>> for slab kernel allocations
>>
>>
>> Forgot to add that im using hfsc and qdiscs like pfifo on classes.
>>
>>
> Maybe some error case I missed in the qdisc patches I'm looking into
> it.
>
> Thanks,
> John
>
>
This is how it looks like when corelated on graph - traffic vs mem
https://ibb.co/njpkqG

Typical hfsc class + qdisc:
### Client interface vlan1616
tc qdisc del dev vlan1616 root
tc qdisc add dev vlan1616 handle 1: root hfsc default 100
tc class add dev vlan1616 parent 1: classid 1:100 hfsc ls m2 200Mbit ul 
m2 200Mbit
tc qdisc add dev vlan1616 parent 1:100 handle 100: pfifo limit 128
### End TM for client interface
tc qdisc del dev vlan1616 ingress
tc qdisc add dev vlan1616 handle ffff: ingress
tc filter add dev vlan1616 parent ffff: protocol ip prio 50 u32 match ip 
src 0.0.0.0/0 police rate 200Mbit burst 200M mtu 32k drop flowid 1:1

And this is same for about 450 vlan interfaces


Good thing is that compared to 4.14.3 i have about 5% less cpu load on 
4.15.0-rc2+

When hfsc will be lockless or tbf - then it will be really huge 
difference in cpu load on x86 when using traffic shaping - so really 
good job John.