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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2023-12-28 17:47:04 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2024-01-08 15:27:15 -0800 |
| commit | 5e0a760b44417f7cadd79de2204d6247109558a0 (patch) | |
| tree | 5f93b6d09d15cb11b0d92e8e4b98dedf1d9ab5b6 /Documentation/networking/packet_mmap.rst | |
| parent | fd37721803c6e73619108f76ad2e12a9aa5fafaf (diff) | |
| download | lwn-5e0a760b44417f7cadd79de2204d6247109558a0.tar.gz lwn-5e0a760b44417f7cadd79de2204d6247109558a0.zip | |
mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER
commit 23baf831a32c ("mm, treewide: redefine MAX_ORDER sanely") has
changed the definition of MAX_ORDER to be inclusive. This has caused
issues with code that was not yet upstream and depended on the previous
definition.
To draw attention to the altered meaning of the define, rename MAX_ORDER
to MAX_PAGE_ORDER.
Link: https://lkml.kernel.org/r/20231228144704.14033-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/networking/packet_mmap.rst')
| -rw-r--r-- | Documentation/networking/packet_mmap.rst | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/Documentation/networking/packet_mmap.rst b/Documentation/networking/packet_mmap.rst index 30a3be3c48f3..dca15d15feaf 100644 --- a/Documentation/networking/packet_mmap.rst +++ b/Documentation/networking/packet_mmap.rst @@ -263,20 +263,20 @@ the name indicates, this function allocates pages of memory, and the second argument is "order" or a power of two number of pages, that is (for PAGE_SIZE == 4096) order=0 ==> 4096 bytes, order=1 ==> 8192 bytes, order=2 ==> 16384 bytes, etc. The maximum size of a -region allocated by __get_free_pages is determined by the MAX_ORDER macro. More -precisely the limit can be calculated as:: +region allocated by __get_free_pages is determined by the MAX_PAGE_ORDER macro. +More precisely the limit can be calculated as:: - PAGE_SIZE << MAX_ORDER + PAGE_SIZE << MAX_PAGE_ORDER In a i386 architecture PAGE_SIZE is 4096 bytes - In a 2.4/i386 kernel MAX_ORDER is 10 - In a 2.6/i386 kernel MAX_ORDER is 11 + In a 2.4/i386 kernel MAX_PAGE_ORDER is 10 + In a 2.6/i386 kernel MAX_PAGE_ORDER is 11 So get_free_pages can allocate as much as 4MB or 8MB in a 2.4/2.6 kernel respectively, with an i386 architecture. User space programs can include /usr/include/sys/user.h and -/usr/include/linux/mmzone.h to get PAGE_SIZE MAX_ORDER declarations. +/usr/include/linux/mmzone.h to get PAGE_SIZE MAX_PAGE_ORDER declarations. The pagesize can also be determined dynamically with the getpagesize (2) system call. @@ -324,7 +324,7 @@ Definitions: (see /proc/slabinfo) <pointer size> depends on the architecture -- ``sizeof(void *)`` <page size> depends on the architecture -- PAGE_SIZE or getpagesize (2) -<max-order> is the value defined with MAX_ORDER +<max-order> is the value defined with MAX_PAGE_ORDER <frame size> it's an upper bound of frame's capture size (more on this later) ============== ================================================================ |