Re: TCP-MD5 checksum failure on x86_64 SMP

Bijay Singh
2010-05-11T08:23:52Z

I need MD5 for my BGP sessions and need the jumbo packets for the IS-IS peering. MTU of 1500 results in LSPs higher that 1500 getting dropped at the peering router.

On 11-May-2010, at 11:57 AM, Eric Dumazet wrote:

> Le mardi 11 mai 2010 à 04:08 +0000, Bijay Singh a écrit :
>> Hi Eric,
>>
>> I guess that makes me the enviable one. So I am keen to test out this feature
>
>> completely, as long as I know what to do as a next step, directions, patches.
>>
>
> MTU > 4000 is not reliable because of high order allocations on typical
> NICS. I am afraid you need NIC able to deliver page fragments.
>
> Its working here (32bit kernel) with a tg3 NIC, but I got following
> message :
>
> ifconfig eth3 mtu 9000
> ...
> [51492.936500] 167731 total pagecache pages
> [51492.936500] 0 pages in swap cache
> [51492.936500] Swap cache stats: add 0, delete 0, find 0/0
> [51492.936500] Free swap = 4192928kB
> [51492.936500] Total swap = 4192928kB
> [51492.936500] 1114110 pages RAM
> [51492.936500] 885761 pages HighMem
> [51492.936500] 77073 pages reserved
> [51492.936500] 134483 pages shared
> [51492.936500] 159131 pages non-shared
> [51492.953027] tg3 0000:14:04.1: eth3: Using a smaller RX standard ring.
> Only 183 out of 511 buffers were allocated successfully
>
> $ ethtool -g eth3
> Ring parameters for eth3:
> Pre-set maximums:
> RX: 511
> RX Mini: 0
> RX Jumbo: 0
> TX: 511
> Current hardware settings:
> RX: 183
> RX Mini: 0
> RX Jumbo: 0
> TX: 511
>
> $ cat /proc/buddyinfo
> Node 0, zone DMA 5 2 1 1 2 2 2 1 0 1 0
> Node 0, zone Normal 4285 1823 248 73 9 5 0 0 0 0 0
> Node 0, zone HighMem 97 199 921 583 383 261 155 117 69 41 649
>
> I know that if I try to stress RX path, I'll get failures.
>
> Could you explain me why you need both big MTUS and TCP-MD5 ?
>
>
>