Word Addressable I/O

WA_CONFIG environment variable

USAGE

(Bourne shell)

WA_CONFIG="512 5 10 1"

export WA_CONFIG

DESCRIPTION

The WA_CONFIG environment variable is used to do some additional buffering on some system to improve the overall I/O performance. Each waread or wawrit instruction will read/write to memory until a page is full before actually do disk I/O. The WA_CONFIG environment variable consist of 4 elements described below.

WA_CONFIG elements

page_size

The page size for each page of the file in Kwords (ex: 256 means 1Mbytes).

nb_page

The maximum number of pages per opened WA files

tot_page

The maximum total number of pages (total amount for all the files, i.e. files can share pages if not needed).

debug_mode

May take the values from 0 to 5. The higher the number, the more verbiage. Recommended value is 1 (only configuration information is printed).

NOTES

The use of the WA_CONFIG environment variable will actually increase the memory consumption of the program proportionally to the page_size, nb_page and tot_page choices of configuration.

Warning: buffering should not be used on other platforms than the NEC computers, otherwise this could result in a lost of performance due to conflict with the already existing system paging capabilities.

AUTHOR

Mario Lépine - RPN

( waopen, wawrit, waread, waclos)