Add usestats to collect resource usage statistics

[Hal Murray]

I just pushed the code.

You will get things like this:

57570 76638.360 3600 19.221 29.499 1541 0 0 0 2984 288288 2123 0 8428
57570 80238.357 3600 20.812 25.956 1062 0 0 0 3024 246608 2274 0 12652
57570 83838.357 3600 23.353 26.497 833 0 0 0 2992 255329 2556 0 16164
57571 1038.358 3600 31.154 31.335 1027 0 0 0 3088 310802 2393 0 20280
57571 4638.357 3600 31.467 28.972 859 0 0 0 3120 266748 2469 0 23676
57571 8238.357 3600 43.700 38.214 1525 0 0 0 2976 369410 3247 0 29748
57571 11838.357 3600 35.270 24.945 644 0 0 0 3112 226024 3155 0 32384
57571 15438.357 3600 46.356 29.400 1439 0 0 0 2856 278092 1971 0 37928

The data is from getrusage().

The last column is the high water mark for the "resident set size" in 
kilobytes.  If anybody figures out exactly what that means, please clue me in.

The above is from a pool server setup with the mrulist limit big enough to 
hold a whole day.  It's still ramping up.

The floating point numbers are user and system CPU usage.  The last line 
shows a total usage of 2.104%.

One of the 0s is page faults.

More into in ./host/docs/monopt.html
or docs/includes/mon-commands.txt





-- 
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