[PATCH -mm v2 3/3] sysv ipc: use auto_msgmnb to desactivate and reactivate msgmnb recomputation

Solofo.Ramangalahy
2008-07-16T09:20:33Z

[-- Attachment #1: ipc-use-auto_msgmnb.patch --]
[-- Type: text/plain, Size: 10478 bytes --]

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

Add /proc/sys/kernel/auto_msgmnb to control automatic recomputation of
/proc/sys/kernel/msgmnb (msg_ctlmnb).

Signed-off-by: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net>
---
Documentation/sysctl/kernel.txt | 35 ++++++++++++++++
include/linux/ipc_namespace.h | 5 ++
ipc/ipc_sysctl.c | 87 ++++++++++++++++++++++++++++++++++++----
ipc/ipcns_notifier.c | 62 +++++++++++++++++++++++++++-
ipc/namespace.c | 2
ipc/util.c | 1
6 files changed, 183 insertions(+), 9 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
@@ -38,6 +38,7 @@ struct ipc_namespace {
atomic_t msg_bytes;
atomic_t msg_hdrs;
int auto_msgmni;
+ int auto_msgmnb;

size_t shm_ctlmax;
size_t shm_ctlall;
@@ -45,6 +46,7 @@ struct ipc_namespace {
int shm_tot;

struct notifier_block ipcns_nb;
+ struct notifier_block ipcns_nb_msgmnb;
};

extern struct ipc_namespace init_ipc_ns;
@@ -56,6 +58,9 @@ extern atomic_t nr_ipc_ns;
extern int register_ipcns_notifier(struct ipc_namespace *);
extern int cond_register_ipcns_notifier(struct ipc_namespace *);
extern void unregister_ipcns_notifier(struct ipc_namespace *);
+extern int register_ipcns_notifier_msgmnb(struct ipc_namespace *);
+extern int cond_register_ipcns_notifier_msgmnb(struct ipc_namespace *);
+extern void unregister_ipcns_notifier_msgmnb(struct ipc_namespace *);
extern int ipcns_notify(unsigned long);

#else /* CONFIG_SYSVIPC */
Index: linux-2.6.26-rc8-mm1-MSGMNB3/ipc/ipc_sysctl.c
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/ipc/ipc_sysctl.c
+++ linux-2.6.26-rc8-mm1-MSGMNB3/ipc/ipc_sysctl.c
@@ -50,6 +50,22 @@ static void ipc_auto_callback(int val)
}
}

+static void ipc_auto_callback_msgmnb(int val)
+{
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
+ if (!val)
+ unregister_ipcns_notifier_msgmnb(ns);
+ else {
+ /*
+ * Re-enable automatic recomputing only if not already
+ * enabled.
+ */
+ ipc_recompute_msgmnb(ns);
+ recompute_msgmni(ns);
+ cond_register_ipcns_notifier_msgmnb(ns);
+ }
+}
+
#ifdef CONFIG_PROC_FS
static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -73,14 +89,24 @@ static int proc_ipc_callback_dointvec(ct

rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);

- if (write && !rc && lenp_bef == *lenp)
+ if (write && !rc && lenp_bef == *lenp) {
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
/*
* Tunable has successfully been changed by hand. Disable its
* automatic adjustment. This simply requires unregistering
* the notifiers that trigger recalculation.
*/
- unregister_ipcns_notifier(current->nsproxy->ipc_ns);
-
+ switch (table->ctl_name) {
+ case KERN_MSGMNI:
+ unregister_ipcns_notifier(ns);
+ break;
+ case KERN_MSGMNB:
+ unregister_ipcns_notifier_msgmnb(ns);
+ break;
+ default:
+ break;
+ }
+ }
return rc;
}

@@ -123,6 +149,34 @@ static int proc_ipcauto_dointvec_minmax(
return rc;
}

+static int proc_ipcauto_dointvec_minmax_msgmnb(ctl_table *table, int write,
+ struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table ipc_table;
+ size_t lenp_bef = *lenp;
+ int oldval;
+ int rc;
+
+ memcpy(&ipc_table, table, sizeof(ipc_table));
+ ipc_table.data = get_ipc(table);
+ oldval = *((int *)(ipc_table.data));
+
+ rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);
+
+ if (write && !rc && lenp_bef == *lenp) {
+ int newval = *((int *)(ipc_table.data));
+ /*
+ * The file "auto_msgmnb" has correctly been set.
+ * React by (un)registering the corresponding tunable, if the
+ * value has changed.
+ */
+ if (newval != oldval)
+ ipc_auto_callback_msgmnb(newval);
+ }
+
+ return rc;
+}
+
#else
#define proc_ipc_doulongvec_minmax NULL
#define proc_ipc_dointvec NULL
@@ -175,16 +229,25 @@ static int sysctl_ipc_registered_data(ct
void __user *newval, size_t newlen)
{
int rc;
-
rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
newlen);

- if (newval && newlen && rc > 0)
+ if (newval && newlen && rc > 0) {
+ struct ipc_namespace *ns = current->nsproxy->ipc_ns;
/*
* Tunable has successfully been changed from userland
*/
- unregister_ipcns_notifier(current->nsproxy->ipc_ns);
-
+ switch (table->ctl_name) {
+ case KERN_MSGMNI:
+ unregister_ipcns_notifier(ns);
+ break;
+ case KERN_MSGMNB:
+ unregister_ipcns_notifier_msgmnb(ns);
+ break;
+ default:
+ break;
+ }
+ }
return rc;
}
#else
@@ -269,6 +332,16 @@ static struct ctl_table ipc_kern_table[]
.extra1 = &zero,
.extra2 = &one,
},
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "auto_msgmnb",
+ .data = &init_ipc_ns.auto_msgmnb,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_ipcauto_dointvec_minmax_msgmnb,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
{}
};

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
@@ -29,7 +29,8 @@ static int ipcns_callback(struct notifie
ns = container_of(self, struct ipc_namespace, ipcns_nb);
switch (action) {
case IPCNS_CPUCHANGED:
- ipc_recompute_msgmnb(ns); /* Fall through */
+ if (ns->auto_msgmnb)
+ ipc_recompute_msgmnb(ns); /* Fall through */
case IPCNS_MEMCHANGED: /* amount of lowmem has changed */
case IPCNS_CREATED:
case IPCNS_REMOVED:
@@ -42,7 +43,8 @@ static int ipcns_callback(struct notifie
* blocking_notifier_call_chain.
* So the ipc ns cannot be freed while we are here.
*/
- recompute_msgmni(ns);
+ if (ns->auto_msgmni)
+ recompute_msgmni(ns);
break;
default:
break;
@@ -88,3 +90,59 @@ int ipcns_notify(unsigned long val)
{
return blocking_notifier_call_chain(&ipcns_chain, val, NULL);
}
+
+static int ipcns_callback_msgmnb(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ struct ipc_namespace *ns;
+ ns = container_of(self, struct ipc_namespace, ipcns_nb_msgmnb);
+ switch (action) {
+ case IPCNS_CPUCHANGED:
+ if (ns->auto_msgmnb)
+ ipc_recompute_msgmnb(ns); /* Fall through */
+ case IPCNS_MEMCHANGED:
+ case IPCNS_CREATED:
+ case IPCNS_REMOVED:
+ if (ns->auto_msgmni)
+ recompute_msgmni(ns);
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+int register_ipcns_notifier_msgmnb(struct ipc_namespace *ns)
+{
+ int rc;
+
+ memset(&ns->ipcns_nb_msgmnb, 0, sizeof(ns->ipcns_nb_msgmnb));
+ ns->ipcns_nb_msgmnb.notifier_call = ipcns_callback_msgmnb;
+ ns->ipcns_nb_msgmnb.priority = IPCNS_CALLBACK_PRI;
+ rc = blocking_notifier_chain_register(&ipcns_chain,
+ &ns->ipcns_nb_msgmnb);
+ if (!rc)
+ ns->auto_msgmnb = 1;
+ return rc;
+}
+
+int cond_register_ipcns_notifier_msgmnb(struct ipc_namespace *ns)
+{
+ int rc;
+
+ memset(&ns->ipcns_nb_msgmnb, 0, sizeof(ns->ipcns_nb_msgmnb));
+ ns->ipcns_nb_msgmnb.notifier_call = ipcns_callback_msgmnb;
+ ns->ipcns_nb_msgmnb.priority = IPCNS_CALLBACK_PRI;
+ rc = blocking_notifier_chain_cond_register(&ipcns_chain,
+ &ns->ipcns_nb_msgmnb);
+ if (!rc)
+ ns->auto_msgmnb = 1;
+ return rc;
+}
+
+void unregister_ipcns_notifier_msgmnb(struct ipc_namespace *ns)
+{
+ blocking_notifier_chain_unregister(&ipcns_chain, &ns->ipcns_nb_msgmnb);
+ ns->auto_msgmnb = 0;
+}
Index: linux-2.6.26-rc8-mm1-MSGMNB3/ipc/namespace.c
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/ipc/namespace.c
+++ linux-2.6.26-rc8-mm1-MSGMNB3/ipc/namespace.c
@@ -26,6 +26,7 @@ static struct ipc_namespace *clone_ipc_n
msg_init_ns(ns);
shm_init_ns(ns);

+ register_ipcns_notifier_msgmnb(ns);
/*
* msgmni has already been computed for the new ipc ns.
* Thus, do the ipcns creation notification before registering that
@@ -98,6 +99,7 @@ void free_ipc_ns(struct kref *kref)
* released the rd lock.
*/
unregister_ipcns_notifier(ns);
+ unregister_ipcns_notifier_msgmnb(ns);
sem_exit_ns(ns);
msg_exit_ns(ns);
shm_exit_ns(ns);
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
@@ -141,6 +141,7 @@ static int __init ipc_init(void)
hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
hotcpu_notifier(ipc_cpu_callback, IPC_CALLBACK_PRI);
register_ipcns_notifier(&init_ipc_ns);
+ register_ipcns_notifier_msgmnb(&init_ipc_ns);
return 0;
}
__initcall(ipc_init);
Index: linux-2.6.26-rc8-mm1-MSGMNB3/Documentation/sysctl/kernel.txt
===================================================================
--- linux-2.6.26-rc8-mm1-MSGMNB3.orig/Documentation/sysctl/kernel.txt
+++ linux-2.6.26-rc8-mm1-MSGMNB3/Documentation/sysctl/kernel.txt
@@ -179,6 +179,41 @@ kernel stack.

==============================================================

+msgmnb
+
+Maximum size in bytes, not in message count, of a single SystemV IPC
+message queue (b stands for bytes).
+
+This value is dynamic and depends on the online cpu count of the
+machine (taking cpu hotplug into account).
+
+Computed values are between MSGMNB and MSGMNB*MSG_CPU_SCALE #define
+constants (currently [16384,65536]).
+
+The exact value is automatically (re)computed, but:
+
+. If the value is positioned from user space (via procfs or sysctl()),
+ then the automatic recomputation is disabled. E.g.:
+
+ # echo 16384 > /proc/sys/kernel/msgmnb
+
+. The automatic recomputation can also be disabled via auto_msgmnb,
+ e.g.:
+
+ # echo 0 > /proc/sys/kernel/auto_msgmnb
+
+. When disabled, the automatic recomputation can be reenabled via
+ auto_msgmnb, e.g.:
+
+ # echo 1 > /proc/sys/kernel/auto_msgmnb
+
+The msgmnb and auto_msgmnb values in each (ipc) namespace are
+independent.
+
+Initially, the msgmnb value is computed automatically: at boot time
+and (ipc) namespace creation.
+
+==============================================================
osrelease, ostype & version:

# cat osrelease

--