This patch adds two more lines of output to /proc/meminfo, CommitLimit
and Committed_AS. On a system running the strict VM overcommit patch,
these are useful bits of information (especially Committed_AS, which
lets you know how close you are to full committment).
This particular patch is part of a patch from the Red Hat Enterprise
Linux 3 kernel, rediffed against 2.4.33-pre1 + the strict VM overcommit
patch I posted earlier. However, the 2.6 kernel contains very similar
code that provides the same output in /proc/meminfo.
Signed-off-by: Barry K. Nathan <[email protected]>
diff -ruN linux-2.4.33-pre1-memA/Documentation/vm/overcommit-accounting linux-2.4.33-pre1-memB/Documentation/vm/overcommit-accounting
--- linux-2.4.33-pre1-memA/Documentation/vm/overcommit-accounting Thu Dec 29 20:39:30 2005
+++ linux-2.4.33-pre1-memB/Documentation/vm/overcommit-accounting Thu Dec 29 20:41:05 2005
@@ -22,6 +22,13 @@
will never kill a process accessing pages it has mapped
except due to a bug (ie report it!)
+The overcommit policy is set via the sysctl `vm.overcommit_memory'.
+
+The overcommit percentage is set via `vm.overcommit_ratio'.
+
+The current overcommit limit and amount committed are viewable in
+/proc/meminfo as CommitLimit and Committed_AS respectively.
+
Gotchas
-------
diff -ruN linux-2.4.33-pre1-memA/fs/proc/proc_misc.c linux-2.4.33-pre1-memB/fs/proc/proc_misc.c
--- linux-2.4.33-pre1-memA/fs/proc/proc_misc.c Thu Dec 29 20:39:30 2005
+++ linux-2.4.33-pre1-memB/fs/proc/proc_misc.c Thu Dec 29 20:41:05 2005
@@ -158,11 +158,9 @@
struct sysinfo i;
int len;
int pg_size ;
- int committed;
+ unsigned long committed;
+ unsigned long allowed;
- /* FIXME: needs to be in headers */
- extern atomic_t vm_committed_space;
-
/*
* display in kilobytes.
*/
@@ -172,6 +170,8 @@
si_swapinfo(&i);
pg_size = page_cache_size - i.bufferram;
committed = atomic_read(&vm_committed_space);
+ allowed = (i.totalram * sysctl_overcommit_ratio / 100)
+ + total_swap_pages;
len = sprintf(page, " total: used: free: shared: buffers: cached:\n"
"Mem: %8Lu %8Lu %8Lu %8Lu %8Lu %8Lu\n"
@@ -199,7 +199,9 @@
"LowTotal: %8lu kB\n"
"LowFree: %8lu kB\n"
"SwapTotal: %8lu kB\n"
- "SwapFree: %8lu kB\n",
+ "SwapFree: %8lu kB\n"
+ "CommitLimit: %8lu kB\n"
+ "Committed_AS: %8lu kB\n",
K(i.totalram),
K(i.freeram),
K(i.sharedram),
@@ -213,7 +215,9 @@
K(i.totalram-i.totalhigh),
K(i.freeram-i.freehigh),
K(i.totalswap),
- K(i.freeswap));
+ K(i.freeswap),
+ K(allowed),
+ K(committed));
return proc_calc_metrics(page, start, off, count, eof, len);
#undef B
diff -ruN linux-2.4.33-pre1-memA/include/linux/mman.h linux-2.4.33-pre1-memB/include/linux/mman.h
--- linux-2.4.33-pre1-memA/include/linux/mman.h Thu Dec 29 20:39:30 2005
+++ linux-2.4.33-pre1-memB/include/linux/mman.h Thu Dec 29 20:41:05 2005
@@ -9,5 +9,7 @@
extern int vm_enough_memory(long pages);
extern void vm_unacct_memory(long pages);
extern void vm_validate_enough(char *x);
+extern atomic_t vm_committed_space;
+extern int sysctl_overcommit_ratio;
#endif /* _LINUX_MMAN_H */
-
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