This patch changes the following defaults:

max_dirty_pages_pct: default from 90 to 75. max allowed from 100 to 99
additional_mem_pool_size: default from 1 to 8 MB
buffer_pool_size: default from 8 to 128 MB
log_buffer_size: default from 1 to 8 MB
read_io_threads/write_io_threads: default from 1 to 4

The log file sizes are untouched because of upgrade issues

Reviewed by: Heikki