Under extreme circumstances - say TCP Segmentation where an ndis_packet can
be up to 64K large- 33 fragments is not an imaginary number… I have reason
to believe that 33 is not the limit when Offloading is performed, and since
Offloading capabilities is queried after initialization, I don’t believe
that NdisMInitializeScatterGatherDma sets such a low limit.
-----Original Message-----
From: xxxxx@hotmail.com [mailto:xxxxx@hotmail.com]
Sent: Thu, January 24, 2002 3:29 PM
To: NT Developers Interest List
Subject: [ntdev] Re: Maximum scatter/gather elements in network driver -
Continued
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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Hmm, even a 64K TCP packet (NDIS_TASK_TCP_LARGE_SEND) would probably
only span 64k / 4K = 16 pages plus maybe some extra fragments for the
MAC/IP/TCP headers. That’s not even close to 33.
I haven’t played with TCP large sends yet, though. Some real live
numbers for the buffer fragment or DMA segment count for large sends
anyone?
Stephan
On Thu, 24 Jan 2002 16:18:01 +0200, “Rosner, Gedon”
wrote:
>
>Under extreme circumstances - say TCP Segmentation where an ndis_packet can
>be up to 64K large- 33 fragments is not an imaginary number… I have reason
>to believe that 33 is not the limit when Offloading is performed, and since
>Offloading capabilities is queried after initialization, I don’t believe
>that NdisMInitializeScatterGatherDma sets such a low limit.
>
>-----Original Message-----
>From: xxxxx@hotmail.com [mailto:xxxxx@hotmail.com]
>Sent: Thu, January 24, 2002 3:29 PM
>To: NT Developers Interest List
>Subject: [ntdev] Re: Maximum scatter/gather elements in network driver -
>Continued
>
>
>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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