diff options
| author | Sourav Panda <souravpanda@google.com> | 2026-08-07 04:00:03 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-08-24 18:43:11 -0700 |
| commit | 34e0849142c317eed68f3a4818dd3808fb1c47db (patch) | |
| tree | ae4bab3466267623a2daf17a8948ea18f38d115b /Documentation | |
| parent | 28b13c3c4c6592da8dd59a7b06655e39665ee624 (diff) | |
mm/hugetlb_cma: support percentage-based hugetlb_cma reservation
Currently, hugetlb_cma reservation only supports absolute sizes (e.g.,
hugetlb_cma=2G or hugetlb_cma=0:1G,1:1G). This can be restrictive in
heterogeneous environments or when deploying common kernel command lines
across machines with different memory capacities.
Add support for percentage-based hugetlb_cma reservation (e.g.,
hugetlb_cma=20% or hugetlb_cma=0:20%,1:10%).
The percentage is calculated against the total memory (for global
settings) or against the node-specific memory (for node-specific settings)
using memblock APIs during early boot.
Link: https://lore.kernel.org/20260807040003.2156630-1-souravpanda@google.com
Signed-off-by: Sourav Panda <souravpanda@google.com>
Acked-by: Usama Arif <usama.arif@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 364c2dce8e70..1af62cd16c9d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2064,8 +2064,14 @@ Kernel parameters hugetlb_cma= [HW,CMA,EARLY] The size of a CMA area used for allocation of gigantic hugepages. Or using node format, the size of a CMA area per node can be specified. - Format: nn[KMGTPE] or (node format) - <node>:nn[KMGTPE][,<node>:nn[KMGTPE]] + The size can be an absolute value (e.g., 2G) or a + percentage of the total memory or node memory (e.g., 20%). + Percentage-derived sizes are rounded down to a multiple of + the architecture's gigantic hugepage size and may become + zero. + Format: nn[KMGTPE] or nn% or (node format) + <node>:nn[KMGTPE][,<node>:nn[KMGTPE]] or + <node>:nn%[,<node>:nn%] The size must be a multiple of the gigantic page size. When using node format, this applies to each per-node size. |