Enable direct I/O for I/O Benchmark

* Really this should've been enabled earlier
* Also increased chunk size

.bin/Scripts/functions/hw_diags.py

@@ -43,7 +43,7 @@ ATTRIBUTES = {
     }
 IO_VARS = {
     'Block Size': 512*1024,
-    'Chunk Size': 16*1024**2,
+    'Chunk Size': 32*1024**2,
     'Minimum Dev Size': 8*1024**3,
     'Minimum Test Size': 10*1024**3,
     'Alt Test Size Factor': 0.01,
@@ -813,7 +813,7 @@ def run_iobenchmark(ticket_number):
                 c = int(IO_VARS['Chunk Size'] / IO_VARS['Block Size'])
                 if skip_extra and i % skip_extra == 0:
                     s += 1
-                cmd = 'sudo dd bs={b} skip={s} count={c} if=/dev/{n} of={o}'.format(
+                cmd = 'sudo dd bs={b} skip={s} count={c} if=/dev/{n} of={o} iflag=direct'.format(
                     b=IO_VARS['Block Size'],
                     s=offset+s,
                     c=c,