[PATCH -mm v2 2/3] sysv ipc: recompute msgmnb (and msgmni) on cpu hotplug addition and removal

Solofo.Ramangalahy
2008-07-16T09:19:48Z

[-- Attachment #1: ipc-recompute-msgmnb-and-msgmni-on-cpu-hotplug-addition-removal.patch --]
[-- Type: text/plain, Size: 3402 bytes --]

From: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net>

As msgmnb is scaled wrt. online cpus, cpu hotplug events should grow
and shrink the value.

Like msgmni with ipc_memory_callback(), the ipc_cpu_callback()
function triggers msgmnb recomputation.

Signed-off-by: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net>

---
include/linux/ipc_namespace.h | 1 +
ipc/ipcns_notifier.c | 8 +++-----
ipc/util.c | 28 ++++++++++++++++++++++++++++
3 files changed, 32 insertions(+), 5 deletions(-)

Index: linux-2.6.26-rc8-mm1-MSGMNB3/include/linux/ipc_namespace.h
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/include/linux/ipc_namespace.h
+++ linux-2.6.26-rc8-mm1-MSGMNB3/include/linux/ipc_namespace.h
@@ -12,6 +12,7 @@
#define IPCNS_MEMCHANGED 0x00000001 /* Notify lowmem size changed */
#define IPCNS_CREATED 0x00000002 /* Notify new ipc namespace created */
#define IPCNS_REMOVED 0x00000003 /* Notify ipc namespace removed */
+#define IPCNS_CPUCHANGED 0x00000004 /* Notify cpu hotplug addition/removal */

#define IPCNS_CALLBACK_PRI 0

Index: linux-2.6.26-rc8-mm1-MSGMNB3/ipc/util.c
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/ipc/util.c
+++ linux-2.6.26-rc8-mm1-MSGMNB3/ipc/util.c
@@ -34,6 +34,7 @@
#include <linux/nsproxy.h>
#include <linux/rwsem.h>
#include <linux/memory.h>
+#include <linux/cpu.h>
#include <linux/ipc_namespace.h>

#include <asm/unistd.h>
@@ -96,6 +97,32 @@ static int ipc_memory_callback(struct no

#endif /* CONFIG_MEMORY_HOTPLUG */

+#ifdef CONFIG_HOTPLUG_CPU
+
+static void ipc_cpu_notifier(struct work_struct *work)
+{
+ ipcns_notify(IPCNS_CPUCHANGED);
+}
+
+static DECLARE_WORK(ipc_cpu_wq, ipc_cpu_notifier);
+
+static int __cpuinit ipc_cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ schedule_work(&ipc_cpu_wq);
+ break;
+ default:
+ break;
+ }
+ return NOTIFY_OK;
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
/**
* ipc_init - initialise IPC subsystem
*
@@ -112,6 +139,7 @@ static int __init ipc_init(void)
msg_init();
shm_init();
hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
+ hotcpu_notifier(ipc_cpu_callback, IPC_CALLBACK_PRI);
register_ipcns_notifier(&init_ipc_ns);
return 0;
}
Index: linux-2.6.26-rc8-mm1-MSGMNB3/ipc/ipcns_notifier.c
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/ipc/ipcns_notifier.c
+++ linux-2.6.26-rc8-mm1-MSGMNB3/ipc/ipcns_notifier.c
@@ -26,16 +26,14 @@ static int ipcns_callback(struct notifie
unsigned long action, void *arg)
{
struct ipc_namespace *ns;
-
+ ns = container_of(self, struct ipc_namespace, ipcns_nb);
switch (action) {
+ case IPCNS_CPUCHANGED:
+ ipc_recompute_msgmnb(ns); /* Fall through */
case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
case IPCNS_CREATED:
case IPCNS_REMOVED:
/*
- * It's time to recompute msgmni
- */
- ns = container_of(self, struct ipc_namespace, ipcns_nb);
- /*
* No need to get a reference on the ns: the 1st job of
* free_ipc_ns() is to unregister the callback routine.
* blocking_notifier_chain_unregister takes the wr lock to do

--