MS160SE usage by the ftp search server

The interface between the CPU and the RAM on the MS160 card gives an access speed of 1 MB/s, for sequential access. Any data read/write is done into one column at a time, with word accesses to an I/O port. Such read/writes must start at a 1 KB boundary. This implies that the postprocess filtering of each potential hit in a column uses about 1 ms.

Since the data searched contains unique filenames, we can report an average of 6 hits for each hit reported by the MS160. With normal use (Max 50 hits), this gives an postprocessing cost of 10 ms. Added to this, we have the searching time of the MS160 chip, which is about 800 ms for simple searches (searching through 128MB of unique file names). The postprocessing CPU overhead and the networking overhead takes approx. 1 ms for each reported hit. In addition, reading directory names from disk takes e.g. 20 ms elapsed time for each reported hit. This gives a total of approximately 1.9 s elapsed for each normal search, which could be reduced significantly if we had all directory names (22 MB) in main memory.

Measurements over an interval of 6195 minutes showed 100 CPU minutes used, 22343 search requests and 1400 navigation requests handled. This gives less than 253 ms CPU usage per request.

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Last modified: Thu Sep 19 00:02:53 MET DST 1996