On 22.04.24 16:18, Maíra Canal wrote:
Commit 839195352d82 ("mm/shuffle: remove dynamic reconfiguration")
removed the dynamic reconfiguration capabilities from the shuffle page
allocator. This means that, now, we don't have any perspective of an
"autodetection of memory-side-cache" that triggers the enablement of the
shuffle page allocator.
IIRC (it's been a while), we never had that autodetection upstream; we
only had the code in place that would never get called. 839195352d82
removed that (dead) code.
Therefore, let the documentation reflect that the only way to enable
the shuffle page allocator is by setting `page_alloc.shuffle=1`.
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 10 ++++------
mm/Kconfig | 7 +++----
2 files changed, 7 insertions(+), 10 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 902ecd92a29f..924bb8ddd8a8 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4170,13 +4170,11 @@
page_alloc.shuffle=
[KNL] Boolean flag to control whether the page allocator
- should randomize its free lists. The randomization may
- be automatically enabled if the kernel detects it is
- running on a platform with a direct-mapped memory-side
- cache, and this parameter can be used to
- override/disable that behavior. The state of the flag
- can be read from sysfs at:
+ should randomize its free lists. This parameter can be
+ used to enable/disable page randomization. The state of
+ the flag can be read from sysfs at:
/sys/module/page_alloc/parameters/shuffle.
+ This parameter is only available if CONFIG_SHUFFLE_PAGE_ALLOCATOR=y.
page_owner= [KNL,EARLY] Boot-time page_owner enabling option.
Storage of the information about who allocated
diff --git a/mm/Kconfig b/mm/Kconfig
index b1448aa81e15..f30a18a0e37d 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -333,10 +333,9 @@ config SHUFFLE_PAGE_ALLOCATOR
While the randomization improves cache utilization it may
negatively impact workloads on platforms without a cache. For
- this reason, by default, the randomization is enabled only
- after runtime detection of a direct-mapped memory-side-cache.
- Otherwise, the randomization may be force enabled with the
- 'page_alloc.shuffle' kernel command line parameter.
+ this reason, by default, the randomization is not enabled even
+ if SHUFFLE_PAGE_ALLOCATOR=y. The randomization may be force enabled
+ with the 'page_alloc.shuffle' kernel command line parameter.
Say Y if unsure.
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
--
Cheers,
David / dhildenb
