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author | David S. Miller <davem@davemloft.net> | 2009-05-17 18:55:57 (GMT) |
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committer | David S. Miller <davem@davemloft.net> | 2009-05-17 18:55:57 (GMT) |
commit | 74392592bbf7e93ef383588e21aea0c1450d6f12 (patch) | |
tree | 086981f9ef51d57a34fbc5fde8095652877cf739 /mm/Kconfig | |
parent | 17e4d43eb6743a92d7667c822a3c3ecd63a9c58e (diff) | |
parent | 0f6f49a8cd0163fdb1723ed29f01fc65177108dc (diff) | |
download | linux-fsl-qoriq-74392592bbf7e93ef383588e21aea0c1450d6f12.tar.xz |
Merge branch 'master' of /home/davem/src/GIT/linux-2.6/
Diffstat (limited to 'mm/Kconfig')
-rw-r--r-- | mm/Kconfig | 30 |
1 files changed, 30 insertions, 0 deletions
@@ -213,6 +213,8 @@ config UNEVICTABLE_LRU will use one page flag and increase the code size a little, say Y unless you know what you are doing. + See Documentation/vm/unevictable-lru.txt for more information. + config HAVE_MLOCK bool default y if MMU=y @@ -223,3 +225,31 @@ config HAVE_MLOCKED_PAGE_BIT config MMU_NOTIFIER bool + +config NOMMU_INITIAL_TRIM_EXCESS + int "Turn on mmap() excess space trimming before booting" + depends on !MMU + default 1 + help + The NOMMU mmap() frequently needs to allocate large contiguous chunks + of memory on which to store mappings, but it can only ask the system + allocator for chunks in 2^N*PAGE_SIZE amounts - which is frequently + more than it requires. To deal with this, mmap() is able to trim off + the excess and return it to the allocator. + + If trimming is enabled, the excess is trimmed off and returned to the + system allocator, which can cause extra fragmentation, particularly + if there are a lot of transient processes. + + If trimming is disabled, the excess is kept, but not used, which for + long-term mappings means that the space is wasted. + + Trimming can be dynamically controlled through a sysctl option + (/proc/sys/vm/nr_trim_pages) which specifies the minimum number of + excess pages there must be before trimming should occur, or zero if + no trimming is to occur. + + This option specifies the initial value of this option. The default + of 1 says that all excess pages should be trimmed. + + See Documentation/nommu-mmap.txt for more information. |