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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) ============== ================================================================ |