Add log_avg_msec option

By default, fio will note an entry in the bw/iops/lat logs for every
IO that is completed. This quickly eats up a lot of disk space
for long running jobs. By setting this option to eg 1000, fio will
average the results logged over 1 second instead. This reduces the
resolution of the log, but makes it more manageable.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index 4733990..afffb9a 100644
--- a/fio.h
+++ b/fio.h
@@ -147,6 +147,7 @@
 	unsigned int write_lat_log;
 	unsigned int write_bw_log;
 	unsigned int write_iops_log;
+	unsigned int log_avg_msec;
 	unsigned int norandommap;
 	unsigned int softrandommap;
 	unsigned int bs_unaligned;