iozone: Update test configs

Update test configurations for iozone. Make large iozone config to
include 'fsync' time in timings as well and test mem/4..2*mem file
sizes. Also change small iozone config to run on node with most free
memory and for sizes node_dirtiable_memory/8..node_dirtiable_memory/2 to
avoid artifacts of node dirty limits.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
iozone: Add config for ramdisk based test

Add config to run iozone test in ramdisk

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
iozone: Add two iozone configs for testing direct IO

Add two more iozone configs. The first is a variant of large config
which uses direct IO to verify block layer handling of direct IO, the
second is a variant of ramdisk config to verify overhead of DIO
submission path.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mel Gorman <mgorman@suse.de>
siege: Use clock() instead of times()

The full information from times is not used but a coarse-grained lock
is required to retrieve the useless information.

Signed-off-by: Mel Gorman <mgorman@suse.de>