Re: Maximum scatter/gather elements in network driver - Continued

Strange. If I use map registers instead of
NdisMInitializeScatterGatherDma I don’t have this problem.

Can someone tell me what it is about NdisMInitializeScatterGatherDma
that limits the number of scatter/gather elements in a send to 33?
More importantly, how do I change this limit (short of going back to
using map registers.

Thanks

----- Original Message -----
From: Peter Craft
To: NT Developers Interest List
Sent: Monday, January 21, 2002 6:18 PM
Subject: [ntdev] Maximum scatter/gather elements in network driver

Something in Win2k (probably NDIS or MSTCP) is
refusing to give transmit packets to my SendPackets
routine if the number of elements in the packet
exceeds 33.

Anyone know why?

Thanks


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Who is the originator of packets with more than 33 buffer fragments?

Although I cannot find any "official" limit for the number of DMA
fragments in a SCATTER_GATHER_LIST in the docs, there probably is some
limit. However, 33 already sounds like a huge number IMHO. Who ever
needs so many packet fragments?

Stephan

On Mon, 21 Jan 2002 18:53:12 -0800, "Peter Craft"
wrote:

>Strange. If I use map registers instead of
>NdisMInitializeScatterGatherDma I don't have this problem.
>
>Can someone tell me what it is about NdisMInitializeScatterGatherDma
>that limits the number of scatter/gather elements in a send to 33?
>More importantly, how do I change this limit (short of going back to
>using map registers.
>
>Thanks

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Let’s see, in the worst case 33*4096 = 135168 bytes. Doesn’t seem that
big to me. In fact I’ve seen over 200 elements when doing IO of more
than 1MB.

Dan

Stephan Wolf wrote:

Who is the originator of packets with more than 33 buffer fragments?

Although I cannot find any “official” limit for the number of DMA
fragments in a SCATTER_GATHER_LIST in the docs, there probably is some
limit. However, 33 already sounds like a huge number IMHO. Who ever
needs so many packet fragments?

Stephan

On Mon, 21 Jan 2002 18:53:12 -0800, “Peter Craft”
wrote:
>
>
>>Strange. If I use map registers instead of
>>NdisMInitializeScatterGatherDma I don’t have this problem.
>>
>>Can someone tell me what it is about NdisMInitializeScatterGatherDma
>>that limits the number of scatter/gather elements in a send to 33?
>>More importantly, how do I change this limit (short of going back to
>>using map registers.
>>
>>Thanks
>>
>
>
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In an NDIS driver??? Is that with IPv6?

Stephan

On Fri, 25 Jan 2002 10:35:56 -0800, Dan Zakaib wrote:

>Let's see, in the worst case 33*4096 = 135168 bytes. Doesn't seem that
>big to me. In fact I've seen over 200 elements when doing IO of more
>than 1MB.
>
>Dan
>
>Stephan Wolf wrote:
>
>> Who is the originator of packets with more than 33 buffer fragments?
>>
>> Although I cannot find any "official" limit for the number of DMA
>> fragments in a SCATTER_GATHER_LIST in the docs, there probably is some
>> limit. However, 33 already sounds like a huge number IMHO. Who ever
>> needs so many packet fragments?
>>
>> Stephan
>> ---
>> On Mon, 21 Jan 2002 18:53:12 -0800, "Peter Craft"
>> wrote:
>>
>>
>>>Strange. If I use map registers instead of
>>>NdisMInitializeScatterGatherDma I don't have this problem.
>>>
>>>Can someone tell me what it is about NdisMInitializeScatterGatherDma
>>>that limits the number of scatter/gather elements in a send to 33?
>>>More importantly, how do I change this limit (short of going back to
>>>using map registers.
>>>
>>>Thanks

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No that was my mistake. I missed the fact the the thread was talking
about NDIS drivers.

Dan

Stephan Wolf wrote:

In an NDIS driver??? Is that with IPv6?

Stephan

On Fri, 25 Jan 2002 10:35:56 -0800, Dan Zakaib wrote:
>
>
>>Let’s see, in the worst case 33*4096 = 135168 bytes. Doesn’t seem that
>>big to me. In fact I’ve seen over 200 elements when doing IO of more
>>than 1MB.
>>
>>Dan
>>
>>Stephan Wolf wrote:
>>
>>
>>>Who is the originator of packets with more than 33 buffer fragments?
>>>
>>>Although I cannot find any “official” limit for the number of DMA
>>>fragments in a SCATTER_GATHER_LIST in the docs, there probably is some
>>>limit. However, 33 already sounds like a huge number IMHO. Who ever
>>>needs so many packet fragments?
>>>
>>>Stephan
>>>—
>>>On Mon, 21 Jan 2002 18:53:12 -0800, “Peter Craft”
>>> wrote:
>>>
>>>
>>>
>>>>Strange. If I use map registers instead of
>>>>NdisMInitializeScatterGatherDma I don’t have this problem.
>>>>
>>>>Can someone tell me what it is about NdisMInitializeScatterGatherDma
>>>>that limits the number of scatter/gather elements in a send to 33?
>>>>More importantly, how do I change this limit (short of going back to
>>>>using map registers.
>>>>
>>>>Thanks
>>>>
>
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