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Algorithm for Calculating Optimum Receive Buffer Size and Number

IP.com Disclosure Number: IPCOM000107151D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 65K

Publishing Venue

IBM

Related People

Scherer, PC: AUTHOR [+2]

Abstract

This article describes algorithms which may be implemented within an automatic configurator or an external spread sheet to calculate the optimum Receive Buffer Size, Number of Receive Buffers and Minimum Work Area for all supported PC Network and Etherand Adapters.

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This is the abbreviated version, containing approximately 52% of the total text.

Algorithm for Calculating Optimum Receive Buffer Size and Number

       This article describes algorithms which may be
implemented within an automatic configurator or an external spread
sheet to calculate the optimum Receive Buffer Size, Number of Receive
Buffers and Minimum Work Area for all supported PC Network and
Etherand Adapters.

      The algorithm starts with a Receive Buffer Size of 512 bytes
and calculates the amount of memory required for this buffer size.
The innovative feature of this algorithm is its ability to adjust for
an additional amount of memory required for configurations with a
large number of links.

      The amount of memory required by the Receive Buffers for a
configuration is calculated using the following equation:
      A = R * int((X - 6)/(R - 8) * N * ((P * L)
+ 1)) where
      A is the Memory Requirement in bytes
      R is the Receive Buffer Size in bytes
      X is the Transmit Buffer Size in bytes
      N is the Number of Transmit Buffers
      P is the Percentage of Links Simultaneously Active (default =
0.025)
      L are the Maximum Number of Link Stations
      int means to round function to the closest integer

      If the memory requirements for the proposed maximum Receive
Buffer Size of 512 bytes exceed the available memory (configured Work
Area), the next smaller Buffer Size of 504 bytes is selected.  As
long as there is no memory fit, the proposed Receive Buffer Size is
decremented by eight bytes and memory recalculated.  This iterative
process continues until a Minimum Buffer Size of 25...