doc: Improve calculation of vm.nr_hugepages

The previous method worked off the full virtual address space, not just
the shared memory usage.

Author: Tsunakawa, Takayuki 
Reviewed-by: Justin Pryzby 
Reviewed-by: Vasundhar Boddapati 

diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index 71f02300c2119b9cf78f5c7a4955f07944983f2b..4929d5529d6b87e99f7a16e4fb7b68f342211934 100644 (file)
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1472,14 +1472,14 @@ export PG_OOM_ADJUST_VALUE=0
     the kernel setting vm.nr_hugepages. To estimate the
     number of huge pages needed, start PostgreSQL
     without huge pages enabled and check the
-    postmaster's VmPeak value, as well as the system's
+    postmaster's anonymous shared memory segment size, as well as the system's
     huge page size, using the /proc file system.  This might
     look like:
 
 $ head -1 $PGDATA/postmaster.pid
 4170
-$ grep ^VmPeak /proc/4170/status
-VmPeak:  6490428 kB
+$ pmap 4170 | awk '/rw-s/ && /zero/ {print $2}'
+6490428K
 $ grep ^Hugepagesize /proc/meminfo
 Hugepagesize:       2048 kB