author Chuck Ebbert <[EMAIL PROTECTED]> Sat, 10 Sep 2005 03:10:15 -0700
committer Linus Torvalds <[EMAIL PROTECTED]> Sat, 10 Sep 2005 04:03:43 -0700
[PATCH] docs: fix misinformation about overcommit_memory
Someone complained about the docs for vm_overcommit_memory being wrong.
This patch copies the text from the vm documentation into procfs.
Signed-off-by: Chuck Ebbert <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
Documentation/filesystems/proc.txt | 42 ++++++++++++++++++++++++++++---------
1 files changed, 32 insertions(+), 10 deletions(-)
diff --git a/Documentation/filesystems/proc.txt
@@ -1241,16 +1241,38 @@ swap-intensive.
-This file contains one value. The following algorithm is used to decide if
-there's enough memory: if the value of overcommit_memory is positive, then
-there's always enough memory. This is a useful feature, since programs often
-malloc() huge amounts of memory 'just in case', while they only use a small
-part of it. Leaving this value at 0 will lead to the failure of such a huge
-malloc(), when in fact the system has enough memory for the program to run.
-On the other hand, enabling this feature can cause you to run out of memory
-and thrash the system to death, so large and/or important servers will want to
-set this value to 0.
+Controls overcommit of system memory, possibly allowing processes
+to allocate (but not use) more memory than is actually available.
+0 - Heuristic overcommit handling. Obvious overcommits of
+ address space are refused. Used for a typical system. It
+ ensures a seriously wild allocation fails while allowing
+ overcommit to reduce swap usage. root is allowed to
+ allocate slighly more memory in this mode. This is the
+1 - Always overcommit. Appropriate for some scientific
+2 - Don't overcommit. The total address space commit
+ for the system is not permitted to exceed swap plus a
+ configurable percentage (default is 50) of physical RAM.
+ Depending on the percentage you use, in most situations
+ this means a process will not be killed while attempting
+ to use already-allocated memory but will receive errors
+ on memory allocation as appropriate.
+Percentage of physical memory size to include in overcommit calculations
+Memory allocation limit = swapspace + physmem * (overcommit_ratio / 100)
+ swapspace = total size of all swap areas
+ physmem = size of physical memory in system
nr_hugepages and hugetlb_shm_group
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html