netdev - Re: [patch net-next v5 0/4] return offloaded stats as default and expose original sw stats

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 23 Jun 2016 17:40:38 +0200
From:	Jiri Pirko <jiri@...nulli.us>
To:	Anuradha Karuppiah <anuradhak@...ulusnetworks.com>
Cc:	Roopa Prabhu <roopa@...ulusnetworks.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	Nogah Frankel <nogahf@...lanox.com>,
	Ido Schimmel <idosch@...lanox.com>,
	Elad Raz <eladr@...lanox.com>,
	Yotam Gigi <yotamg@...lanox.com>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
	John Linville <linville@...driver.com>,
	Thomas Graf <tgraf@...g.ch>,
	Andy Gospodarek <gospo@...ulusnetworks.com>,
	Scott Feldman <sfeldma@...il.com>, sd@...asysnail.net,
	eranbe@...lanox.com, Alexei Starovoitov <ast@...mgrid.com>,
	Eric Dumazet <edumazet@...gle.com>,
	"hannes@...essinduktion.org" <hannes@...essinduktion.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	David Ahern <dsa@...ulusnetworks.com>
Subject: Re: [patch net-next v5 0/4] return offloaded stats as default and
 expose original sw stats

Thu, Jun 23, 2016 at 05:11:26PM CEST, anuradhak@...ulusnetworks.com wrote:
>>>>> we can't separate CPU and HW stats there. In some cases (or ASICs) HW
>>>>> counters do
>>>>> not include CPU generated packets....you will have to add CPU
>>>>> generated pkt counters to the
>>>>> hw counters for such virtual device stats.
>>>> Can you please provide and example how that could happen?
>>>
>>>example is the bridge vlan stats I mention below. These are usually counted
>>>by attaching hw virtual counter resources. And CPU generated packets
>>>in some cases maybe setup to bypass the ASIC pipeline because the CPU
>>>has already made the required decisions. So, they may not be counted by
>>>by such hw virtual counters.
>>
>> Bypass ASIC? How do the packets get on the wire?
>>
>
>Bypass the "forwarding pipeline" in the ASIC that is. Obviously the
>ASIC ships the CPU generated packet out of the switch/front-panel
>port. Continuing Roopa's example of vlan netdev stats.... To get the
>HW stats counters are typically tied to the ingress and egress vlan hw
>entries. All the incoming packets are subject to the ingress vlan
>lookup irrespective of whether they get punted to the CPU or whether
>they are forwarded to another front panel port. In that case the
>ingress HW stats does represent all packets. However for CPU
>originated packets egress vlan lookups are bypassed in the ASIC (this
>is common forwarding option in most ASICs) and the packet shipped as
>is out of front-panel port specified by the CPU. Which means these
>packets will NOT be counted against the egress VLAN HW counter; hence
>the need for summation.

Driver will know about this, and will provide the stats accordignly to
the core. Who else than driver should resolve this.