mirror of
https://github.com/brain-hackers/linux-brain.git
synced 2024-06-09 23:36:23 +09:00
b693d0b372
The documentation is in a format that is very close to ReST format. The conversion is actually: - add blank lines in order to identify paragraphs; - fixing tables markups; - adding some lists markups; - marking literal blocks; - adjust some title markups. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
42 lines
1.4 KiB
ReStructuredText
42 lines
1.4 KiB
ReStructuredText
====================
|
|
HugeTLBpage on ARM64
|
|
====================
|
|
|
|
Hugepage relies on making efficient use of TLBs to improve performance of
|
|
address translations. The benefit depends on both -
|
|
|
|
- the size of hugepages
|
|
- size of entries supported by the TLBs
|
|
|
|
The ARM64 port supports two flavours of hugepages.
|
|
|
|
1) Block mappings at the pud/pmd level
|
|
--------------------------------------
|
|
|
|
These are regular hugepages where a pmd or a pud page table entry points to a
|
|
block of memory. Regardless of the supported size of entries in TLB, block
|
|
mappings reduce the depth of page table walk needed to translate hugepage
|
|
addresses.
|
|
|
|
2) Using the Contiguous bit
|
|
---------------------------
|
|
|
|
The architecture provides a contiguous bit in the translation table entries
|
|
(D4.5.3, ARM DDI 0487C.a) that hints to the MMU to indicate that it is one of a
|
|
contiguous set of entries that can be cached in a single TLB entry.
|
|
|
|
The contiguous bit is used in Linux to increase the mapping size at the pmd and
|
|
pte (last) level. The number of supported contiguous entries varies by page size
|
|
and level of the page table.
|
|
|
|
|
|
The following hugepage sizes are supported -
|
|
|
|
====== ======== ==== ======== ===
|
|
- CONT PTE PMD CONT PMD PUD
|
|
====== ======== ==== ======== ===
|
|
4K: 64K 2M 32M 1G
|
|
16K: 2M 32M 1G
|
|
64K: 2M 512M 16G
|
|
====== ======== ==== ======== ===
|