Extracting fields from logs

[kandulasrinivas]

I have a log file with below content

20120316.051652 Fr I perf Thread-9807784[10.xx.xx.x]/xxxxxx xxxxxxx xxxxxxx 725 100 787234600 2107768832

20120316.051652 Fr I perf Thread-9807750[10.xx.xx.x]/xxxxxxx xxxxxxx xxxxxxx 921 100 790443496 2107768832

How can i add the values that are present in 9 th column of line example in the above line
i want to add 725 + 921 and print the sum of it.

[Ayn]

... | rex "^(?:\S+\s){7}(?<myfield>\d+)" | accum myfield AS myfield_sum