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Managing Realeyes Memory

Jul 23, 2009, 07:32 (6 Talkback[s])
(Other stories by Jim Sansing)

[ Thanks to JJS for this link. ]

"The reason I do my own memory management is to avoid fragmentation. The Realeyes IDS manages a lot of sessions simultaneously, so memory has to be used efficiently as possible. If a buffer were allocated for exactly the size of a packet's data, the overall buffer space would develop lots of pockets of unusable space. But to set the size of data buffers to the largest allowed by the Internet Protocol would also be inefficient, because there are a huge number of tinygrams in network traffic.

"The solution is a compromise. I allocate fixed size buffers in sizes that are designed to waste as little space as possible. The smallest is 64 bytes. The next is 105 bytes, and the next, 128 bytes. So if 56 bytes are needed, the first size buffer is allocated. If 65 bytes are needed, the second. And if 108 bytes are needed, the third."

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