From: Or Gerlitz <ogerlitz@mellanox•com>
To: Jerry Chu <hkchu@google•com>,
Eric Dumazet <eric.dumazet@gmail•com>,
David Miller <davem@davemloft•net>
Cc: Eric Dumazet <edumazet@google•com>,
Herbert Xu <herbert@gondor•apana.org.au>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
Yan Burman <yanb@mellanox•com>,
Shlomo Pongratz <shlomop@mellanox•com>
Subject: Re: [PATCH net-next V2 1/3] net: Add GRO support for UDP encapsulating protocols
Date: Thu, 9 Jan 2014 08:35:07 +0200 [thread overview]
Message-ID: <52CE431B.6010109@mellanox.com> (raw)
In-Reply-To: <CAPshTChSSB8mycXMXSJ656tpBGDqyjUF37+V2S2eAPQs47gJ2A@mail.gmail.com>
On 09/01/2014 05:12, Jerry Chu wrote:
> On Wed, Jan 8, 2014 at 12:02 AM, Or Gerlitz <ogerlitz@mellanox•com> wrote:
>> On 08/01/2014 00:11, Jerry Chu wrote:
>>> On Tue, Jan 7, 2014 at 12:37 PM, Or Gerlitz <or.gerlitz@gmail•com> wrote:
>>>> On Tue, Jan 7, 2014 at 10:32 PM, Eric Dumazet <eric.dumazet@gmail•com>
>>>> wrote:
>>>>> On Tue, 2014-01-07 at 22:19 +0200, Or Gerlitz wrote:
>>>>>> On Tue, Jan 7, 2014 at 6:33 PM, Eric Dumazet <eric.dumazet@gmail•com>
>>>>>> wrote:
>>>>>>> On Tue, 2014-01-07 at 17:29 +0200, Or Gerlitz wrote:
>>>>>>>> +
>>>>>>>> +#define MAX_UDP_PORT (1 << 16)
>>>>>>>> +extern const struct net_offload __rcu *udp_offloads[MAX_UDP_PORT];
>>>>>>> Thats 512 KB of memory.
>>>>>>> This will greatly impact forwarding performance of UDP packets with
>>>>>>> random ports, and will increase kernel memory size for embedded
>>>>>>> devices.
>>>>>> Re forwarding, are you referring to the case where the forwarded
>>>>>> packets are encapsulated? packets which are not encapusalted will be
>>>>>> flushed in the gro receive handler (this went out by mistake in V2 but
>>>>>> exists in V1) if skb->encapsulation isn't set.
>>>>>>
>>>>> How do you know encapsulation must be tried for a given incoming
>>>>> packet ? NIC do not magically sets skb->encapsulation I think...
>>>> So here's the thing, per my understanding we want to GRO only received
>>>> **encapsulated** packets whose checksum status is != CHECKSUM_NONE
>>> What's wrong with GRO'ing pkts whose csum == CHECKSUM_NONE?
>>
>> I am not sure, intuitively it sounds a bit wrong to me, empirically, it
>> doesn't work for udp encapsulated / vxlan
>> traffic, I got drops from the tcp stack in tcp_rcv_established() -- if
>> GRO-ed packets carry CHECKSUM_NONE
>> we arrive to the csum_error label, which means that
>> tcp_checksum_complete_user() failed for them
> This is odd because if pkts have been aggregated successfully,
> tcp4_gro_receive() should've skb_checksum() and turned CHECKSUM_NONE
> into CHECKSUM_UNNECESSARY. (I think i've already tested this
> case with my GRE-GRO patch on a NIC that sends up pkts w/ CHECKSUM_NONE.
>
> But granted there are a lot of csum related bugs in the current code. I just spent half a day scratching my head on a very low thruput number with my GRE patch over a GRE tunnel w/ csum flag on. I just tracked it down to be buggy TSO/GRE code that will produce bad csum on the tx side.
The "there are a lot of csum related bugs in the current code" comment
sounds really bad, how do we get into a better place? can you point on
the buggy TSO code that produced bad csum on the tx side?
next prev parent reply other threads:[~2014-01-09 6:35 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-07 15:29 [PATCH net-next V2 0/3] net: Add GRO support for UDP encapsulating protocols Or Gerlitz
2014-01-07 15:29 ` [PATCH net-next V2 1/3] " Or Gerlitz
2014-01-07 16:33 ` Eric Dumazet
2014-01-07 20:19 ` Or Gerlitz
2014-01-07 20:32 ` Eric Dumazet
2014-01-07 20:37 ` Or Gerlitz
2014-01-07 21:38 ` Eric Dumazet
2014-01-08 8:04 ` Or Gerlitz
[not found] ` <1389182291.26646.79.camel@edumazet-glaptop2.roam.corp.google.com>
2014-01-08 12:15 ` Or Gerlitz
2014-01-07 22:11 ` Jerry Chu
2014-01-08 8:02 ` Or Gerlitz
2014-01-09 3:12 ` Jerry Chu
2014-01-09 6:35 ` Or Gerlitz [this message]
2014-01-09 7:19 ` Or Gerlitz
2014-01-07 18:44 ` Tom Herbert
2014-01-07 20:21 ` Or Gerlitz
2014-01-07 23:04 ` Tom Herbert
2014-01-08 16:11 ` Or Gerlitz
2014-01-08 16:29 ` Tom Herbert
2014-01-08 16:31 ` Or Gerlitz
2014-01-07 21:19 ` David Miller
2014-01-07 21:40 ` Tom Herbert
2014-01-07 15:29 ` [PATCH net-next V2 2/3] net: Export gro_find_by_type helpers Or Gerlitz
2014-01-07 15:29 ` [PATCH net-next V2 3/3] net: Add GRO support for vxlan traffic Or Gerlitz
2014-01-07 16:34 ` Eric Dumazet
2014-01-07 19:43 ` Or Gerlitz
2014-01-07 20:04 ` Eric Dumazet
2014-01-07 20:10 ` Or Gerlitz
2014-01-07 18:08 ` Tom Herbert
2014-01-07 19:43 ` Or Gerlitz
2014-01-07 20:02 ` Eric Dumazet
2014-01-07 20:12 ` Or Gerlitz
2014-01-07 21:09 ` Tom Herbert
2014-01-08 9:45 ` Or Gerlitz
[not found] ` <CAJZOPZLsMvmHwmMjhsuKb__2HncMXMm=p6UFnT4XX5d8hZnGxw@mail.gmail.com>
2014-01-07 19:52 ` Tom Herbert
2014-01-07 16:45 ` [PATCH net-next V2 0/3] net: Add GRO support for UDP encapsulating protocols Eric Dumazet
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