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SubjectRe: packet re-ordering on SMP machines.
Alan Cox wrote:
> On Sun, 2002-08-25 at 08:18, Ben Greear wrote:
>
>>By re-ordered, I mean that a method called from process_backlog in dev.c
>>is being handed packets in a different order than they are being poked into
>>the driver with hard_start_xmit on the other interface. If each CPU can be running the
>>process_backlog, then I can see how this could be happening.
>>
>>
>>1) Is this expected behaviour?
>
> Yes
>
>
>>2) Is there any standard (ie configurable) way to enforce strict ordering on an
>> SMP system?
>
> No
>
>
>>3) If answer to 2 is no, would you all be interested in a patch that
>> did allow strict ordering (if indeed I can figure out how to write one)?
>
>
> You should never need it. Ethernet, hubs, switches, routers, internet
> backbones etc will all cause packet re-ordering. You should also expect
> the percentage of re-ordered frames on the net to rise and rise.

I would like to detect the number of pkts that such backbone hardware does
re-order, so if my end machine is also re-ordering, I cannot get valid
numbers.

Thanks,
Ben

>
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--
Ben Greear <greearb@candelatech.com> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear


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