Tested with 1, 2, 4 and 8 dd processes. I benchmarked 4 kernels:
- with vm_page_alloc_pages, with pcpu caches
- without vm_page_alloc_pages, with pcpu caches
- with vm_page_alloc_pages, without pcpu caches
- without vm_page_alloc_pages, without pcpu caches

x alloc_pages_no_pcpu.1procs.cooked
+ no_alloc_pages_no_pcpu.1procs.cooked
+--------------------------------------------------------------------------+
|                     +                                                    |
|         +           +                                          x       x |
|+   +  ++++          +                     x            x    x xx    x  xx|
|   |_____M_A______|                                    |________A________||
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     3345.7013     3392.6311     3378.2825     3377.9388     14.246249
+  10     3278.0832     3311.6355     3291.9553     3295.1339     11.769459
Difference at 95.0% confidence
	-82.8049 +/- 12.2774
	-2.45134% +/- 0.358189%
	(Student's t, pooled s = 13.0667)
x alloc_pages_w_pcpu.1procs.cooked
+ no_alloc_pages_w_pcpu.1procs.cooked
+--------------------------------------------------------------------------+
|                                                       +    ++     x      |
|x     x                                          +xx  x++ +**+     xx     |
|                       |________________________A_____|_MAM__|___________||
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     3120.0065       3299.51     3267.7312     3246.4797     64.995586
+  10     3249.7287      3281.193      3272.653     3270.4812     9.5884696
No difference proven at 95.0% confidence
x alloc_pages_no_pcpu.2procs.cooked
+ no_alloc_pages_no_pcpu.2procs.cooked
+--------------------------------------------------------------------------+
|++  +++++    ++ +                                          xx xx x  x x  x|
|  |___MA_____|                                               |___MA___|   |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     2931.9473     2974.9755     2949.5663     2951.8831     14.284996
+  10     2747.5345     2798.4738     2767.2834      2770.473      17.24405
Difference at 95.0% confidence
	-181.41 +/- 14.8774
	-6.14557% +/- 0.491626%
	(Student's t, pooled s = 15.8338)
x alloc_pages_w_pcpu.2procs.cooked
+ no_alloc_pages_w_pcpu.2procs.cooked
+--------------------------------------------------------------------------+
|                                                              +           |
|+       x     xx    x              +xx + x x+x +  x        + ++          +|
|                |__________|___A____M_________|_A____M_______________|    |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     2713.4561     2825.3709     2787.5555     2773.7636     39.987149
+  10     2691.6086     2885.7081     2832.4661     2819.5548     55.332784
Difference at 95.0% confidence
	45.7912 +/- 45.3577
	1.65087% +/- 1.64455%
	(Student's t, pooled s = 48.2736)
x alloc_pages_no_pcpu.4procs.cooked
+ no_alloc_pages_no_pcpu.4procs.cooked
+--------------------------------------------------------------------------+
|+                    +                                                   x|
|+ ++                 +++ ++                       xx x  x    x        xxxx|
|   |__________A______M____|                          |_________A_M_______||
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     1852.5145     1975.5109     1933.8786     1921.7409     52.495228
+  10     1584.3654     1721.4234     1696.0756     1660.9451     60.293938
Difference at 95.0% confidence
	-260.796 +/- 53.1146
	-13.5708% +/- 2.60877%
	(Student's t, pooled s = 56.5292)
x alloc_pages_w_pcpu.4procs.cooked
+ no_alloc_pages_w_pcpu.4procs.cooked
+--------------------------------------------------------------------------+
|+       ++  +    x      +  x  x   x    x x    + x   +   x *            + +|
|        |________________|_________A_MA____________|___________|          |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     1560.4438     1740.1142     1644.9255     1651.8693     57.342316
+  10      1485.592      1804.172     1638.4506     1639.8758     121.32948
No difference proven at 95.0% confidence
x alloc_pages_no_pcpu.8procs.cooked
+ no_alloc_pages_no_pcpu.8procs.cooked
+--------------------------------------------------------------------------+
|        +                                                      xx  x      |
|++ ++++++          +                                          xxx xxx    x|
| |___MA____|                                                   |_MA__|    |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     692.66453     704.11884     695.52558     696.26977     3.4148512
+  10     624.54828     645.19947     630.29559     631.10754     5.7243569
Difference at 95.0% confidence
	-65.1622 +/- 4.42855
	-9.35876% +/- 0.620969%
	(Student's t, pooled s = 4.71325)
x alloc_pages_w_pcpu.8procs.cooked
+ no_alloc_pages_w_pcpu.8procs.cooked
+--------------------------------------------------------------------------+
|        +                 x  x                                            |
|+ +  +  +                xx++x ++ x  +     x        x      x             x|
|   |_____________MA____|_______M|_______A_______________|                 |
+--------------------------------------------------------------------------+
    N           Min           Max        Median           Avg        Stddev
x  10     630.73949     667.16514     635.24667      641.6488     12.797614
+  10     611.44524     639.82919     624.80191     624.98463     10.947984
Difference at 95.0% confidence
	-16.6642 +/- 11.1894
	-2.59709% +/- 1.71785%
	(Student's t, pooled s = 11.9088)