On 2/21/23 11:27, Vlastimil Babka wrote:
> Incidentally, did you observe any improvements by [2] with your test,
> especially as the batch freeing side also no longer does checking under zone
> lock?
>
> Thanks!
>
I finally managed to repeat the benchmark to see the effects of
disabling alloc and free sanity checks by default ("mm, page_alloc:
reduce page alloc/free sanity checks"; results below).
Average huge page allocation latency drastically reduces by over 90% in
the single core case. However i can't see any real improvements for the
free operation.
---
Measurement results for the batch allocation benchmark for different
core counts: Internally used functions are alloc_pages_node() for
allocation (get) and __free_pages() for free (put).
Compared kernel versions are from the mm-unstable branch:
- Reference version (without the mentioned patch):
daf4bcbf2b72 ("mm: cma: make kobj_type structure constant")
- Patched version:
60114678f165 ("mm-page_alloc-reduce-page-alloc-free-sanity-checks-fix")
Normale pages
+-------+------+-------+---------+------+-------+---------+
| cores | base | patch | diff | base | patch | diff |
| | get | get | get | put | put | put |
| | (ns) | (ns) | | (ns) | (ns) | |
+-------+------+-------+---------+------+-------+---------+
| 1 | 122 | 118 | (-3.3%) | 118 | 116 | (-1.7%) |
| 2 | 133 | 130 | (-2.3%) | 130 | 123 | (-5.4%) |
| 3 | 136 | 132 | (-2.9%) | 175 | 162 | (-7.4%) |
| 4 | 161 | 149 | (-7.5%) | 241 | 226 | (-6.2%) |
| 6 | 247 | 228 | (-7.7%) | 366 | 344 | (-6.0%) |
| 8 | 331 | 304 | (-8.2%) | 484 | 456 | (-5.8%) |
| 10 | 416 | 390 | (-6.2%) | 615 | 578 | (-6.0%) |
| 12 | 502 | 472 | (-6.0%) | 727 | 687 | (-5.5%) |
| 14 | 584 | 552 | (-5.5%) | 862 | 816 | (-5.3%) |
| 16 | 669 | 632 | (-5.5%) | 967 | 923 | (-4.6%) |
| 20 | 833 | 787 | (-5.5%) | 1232 | 1164 | (-5.5%) |
| 24 | 999 | 944 | (-5.5%) | 1462 | 1384 | (-5.3%) |
+-------+------+-------+---------+------+-------+---------+
Huge Pages
+-------+------+-------+----------+-------+-------+---------+
| cores | base | patch | diff | base | patch | diff |
| | get | get | get | put | put | put |
| | (ns) | (ns) | | (ns) | (ns) | |
+-------+------+-------+----------+-------+-------+---------+
| 1 | 3148 | 177 | (-94.4%) | 2946 | 2872 | (-2.5%) |
| 2 | 3404 | 596 | (-82.5%) | 3318 | 3306 | (-0.4%) |
| 3 | 3581 | 950 | (-73.5%) | 3401 | 3358 | (-1.3%) |
| 4 | 3651 | 1284 | (-64.8%) | 3562 | 3616 | (1.5%) |
| 6 | 3568 | 1929 | (-45.9%) | 4478 | 4564 | (1.9%) |
| 8 | 3605 | 2328 | (-35.4%) | 5658 | 5546 | (-2.0%) |
| 10 | 4093 | 2935 | (-28.3%) | 6758 | 6457 | (-4.5%) |
| 12 | 4778 | 3540 | (-25.9%) | 7698 | 7565 | (-1.7%) |
| 14 | 5565 | 4097 | (-26.4%) | 8748 | 8810 | (0.7%) |
| 16 | 6364 | 4725 | (-25.8%) | 9942 | 10103 | (1.6%) |
| 20 | 8014 | 5915 | (-26.2%) | 12509 | 12772 | (2.1%) |
| 24 | 8732 | 7138 | (-18.3%) | 15217 | 15433 | (1.4%) |
+-------+------+-------+----------+-------+-------+---------+
>>
>> [1] https://lore.kernel.org/lkml/1d468148-936f-8816-eb71-1662f2d4945b@xxxxxxx/
>> [2] https://lore.kernel.org/linux-mm/20230216095131.17336-1-vbabka@xxxxxxx/
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