| Message ID | 20240422142007.1062231-1-mcanal@igalia.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Update shuffle documentation to match its current state | expand |
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@igalia.com> > --- > 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@redhat.com>
Maíra Canal <mcanal@igalia.com> writes: > 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. > > 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@igalia.com> > --- > Documentation/admin-guide/kernel-parameters.txt | 10 ++++------ > mm/Kconfig | 7 +++---- > 2 files changed, 7 insertions(+), 10 deletions(-) Applied, thanks. jon
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.
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. 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@igalia.com> --- Documentation/admin-guide/kernel-parameters.txt | 10 ++++------ mm/Kconfig | 7 +++---- 2 files changed, 7 insertions(+), 10 deletions(-)