(split) LDP: Update original to LDP v3.65

[linuxjm/LDP_man-pages.git] / original / man2 / shmget.2

diff --git a/original/man2/shmget.2 b/original/man2/shmget.2
index 5d93929..09e43c1 100644 (file)
--- a/original/man2/shmget.2
+++ b/original/man2/shmget.2
@@ -35,7 +35,7 @@
 .\"    Language and formatting clean-ups
 .\"    Added notes on /proc files
 .\"
-.TH SHMGET 2 2013-04-19 "Linux" "Linux Programmer's Manual"
+.TH SHMGET 2 2014-04-17 "Linux" "Linux Programmer's Manual"
 .SH NAME
 shmget \- allocates a System V shared memory segment
 .SH SYNOPSIS
@@ -264,14 +264,23 @@ The following limits on shared memory segment resources affect the
 call:
 .TP
 .B SHMALL
-System wide maximum of shared memory pages
-(on Linux, this limit can be read and modified via
-.IR /proc/sys/kernel/shmall ).
+System wide maximum of shared memory pages.
+Since Linux 2.2, the default value for this limit is
+
+    SHMMAX / PAGE_SIZE * (SHMMNI / 16)
+
+Assuming a 4kB page size, this formula yields (since Linux 2.4) the value
+2^20 (2,097,152).
+
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmall .
 .TP
 .B SHMMAX
-Maximum size in bytes for a shared memory segment: policy dependent
-(on Linux, this limit can be read and modified via
-.IR /proc/sys/kernel/shmmax ).
+Maximum size in bytes for a shared memory segment.
+Since Linux 2.2, the default value of this limit is 0x2000000 (32MB).
+
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmmax .
 .TP
 .B SHMMIN
 Minimum size in bytes for a shared memory segment: implementation
@@ -280,10 +289,12 @@ dependent (currently 1 byte, though
 is the effective minimum size).
 .TP
 .B SHMMNI
-System wide maximum number of shared memory segments: implementation
-dependent (currently 4096, was 128 before Linux 2.3.99;
-on Linux, this limit can be read and modified via
-.IR /proc/sys/kernel/shmmni ).
+System wide maximum number of shared memory segments.
+In Linux 2.2, the default value for this limit was 128;
+since Linux 2.4, the default value is 4096.
+
+On Linux, this limit can be read and modified via
+.IR /proc/sys/kernel/shmmni .
 .\" Kernels between 2.4.x and 2.6.8 had an off-by-one error that meant
 .\" that we could create one more segment than SHMMNI -- MTK
 .\" This /proc file is not available in Linux 2.2 and earlier -- MTK
@@ -312,7 +323,7 @@ would more clearly show its function.
 .BR shm_overview (7),
 .BR svipc (7)
 .SH COLOPHON
-This page is part of release 3.64 of the Linux
+This page is part of release 3.65 of the Linux
 .I man-pages
 project.
 A description of the project,