diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 40 | ||||
| -rw-r--r-- | Documentation/admin-guide/mm/hugetlbpage.rst | 35 |
2 files changed, 62 insertions, 13 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 4379c6ac3265..f4d123b57c5b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -834,12 +834,15 @@ See also Documentation/networking/decnet.txt. default_hugepagesz= - [same as hugepagesz=] The size of the default - HugeTLB page size. This is the size represented by - the legacy /proc/ hugepages APIs, used for SHM, and - default size when mounting hugetlbfs filesystems. - Defaults to the default architecture's huge page size - if not specified. + [HW] The size of the default HugeTLB page. This is + the size represented by the legacy /proc/ hugepages + APIs. In addition, this is the default hugetlb size + used for shmget(), mmap() and mounting hugetlbfs + filesystems. If not specified, defaults to the + architecture's default huge page size. Huge page + sizes are architecture dependent. See also + Documentation/admin-guide/mm/hugetlbpage.rst. + Format: size[KMG] deferred_probe_timeout= [KNL] Debugging option to set a timeout in seconds for @@ -1479,13 +1482,24 @@ hugepages using the cma allocator. If enabled, the boot-time allocation of gigantic hugepages is skipped. - hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. - hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. - On x86-64 and powerpc, this option can be specified - multiple times interleaved with hugepages= to reserve - huge pages of different sizes. Valid pages sizes on - x86-64 are 2M (when the CPU supports "pse") and 1G - (when the CPU supports the "pdpe1gb" cpuinfo flag). + hugepages= [HW] Number of HugeTLB pages to allocate at boot. + If this follows hugepagesz (below), it specifies + the number of pages of hugepagesz to be allocated. + If this is the first HugeTLB parameter on the command + line, it specifies the number of pages to allocate for + the default huge page size. See also + Documentation/admin-guide/mm/hugetlbpage.rst. + Format: <integer> + + hugepagesz= + [HW] The size of the HugeTLB pages. This is used in + conjunction with hugepages (above) to allocate huge + pages of a specific size at boot. The pair + hugepagesz=X hugepages=Y can be specified once for + each supported huge page size. Huge page sizes are + architecture dependent. See also + Documentation/admin-guide/mm/hugetlbpage.rst. + Format: size[KMG] hung_task_panic= [KNL] Should the hung task detector generate panics. diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst index 1cc0bc78d10e..5026e58826e2 100644 --- a/Documentation/admin-guide/mm/hugetlbpage.rst +++ b/Documentation/admin-guide/mm/hugetlbpage.rst @@ -100,6 +100,41 @@ with a huge page size selection parameter "hugepagesz=<size>". <size> must be specified in bytes with optional scale suffix [kKmMgG]. The default huge page size may be selected with the "default_hugepagesz=<size>" boot parameter. +Hugetlb boot command line parameter semantics +hugepagesz - Specify a huge page size. Used in conjunction with hugepages + parameter to preallocate a number of huge pages of the specified + size. Hence, hugepagesz and hugepages are typically specified in + pairs such as: + hugepagesz=2M hugepages=512 + hugepagesz can only be specified once on the command line for a + specific huge page size. Valid huge page sizes are architecture + dependent. +hugepages - Specify the number of huge pages to preallocate. This typically + follows a valid hugepagesz or default_hugepagesz parameter. However, + if hugepages is the first or only hugetlb command line parameter it + implicitly specifies the number of huge pages of default size to + allocate. If the number of huge pages of default size is implicitly + specified, it can not be overwritten by a hugepagesz,hugepages + parameter pair for the default size. + For example, on an architecture with 2M default huge page size: + hugepages=256 hugepagesz=2M hugepages=512 + will result in 256 2M huge pages being allocated and a warning message + indicating that the hugepages=512 parameter is ignored. If a hugepages + parameter is preceded by an invalid hugepagesz parameter, it will + be ignored. +default_hugepagesz - Specify the default huge page size. This parameter can + only be specified once on the command line. default_hugepagesz can + optionally be followed by the hugepages parameter to preallocate a + specific number of huge pages of default size. The number of default + sized huge pages to preallocate can also be implicitly specified as + mentioned in the hugepages section above. Therefore, on an + architecture with 2M default huge page size: + hugepages=256 + default_hugepagesz=2M hugepages=256 + hugepages=256 default_hugepagesz=2M + will all result in 256 2M huge pages being allocated. Valid default + huge page size is architecture dependent. + When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages`` indicates the current number of pre-allocated huge pages of the default size. Thus, one can use the following command to dynamically allocate/deallocate |