[RFC PATCH 2/4] [RESEND] Scaling msgmni to the number of ipc namespaces

Nadia.Derbey
2008-01-14T15:58:31Z

[-- Attachment #1: ipc_scale_msgmni_with_namespaces.patch --]
[-- Type: text/plain, Size: 2875 bytes --]

[PATCH 02/04]

Since all the namespaces see the same amount of memory (the total one)
this patch introduces a new variable that counts the ipc namespaces and
divides msg_ctlmni by this counter.

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>

---
include/linux/ipc.h | 1 +
ipc/msg.c | 8 ++++++--
ipc/util.c | 7 +++++++
3 files changed, 14 insertions(+), 2 deletions(-)

Index: linux-2.6.24-rc7/include/linux/ipc.h
===================================================================
--- linux-2.6.24-rc7.orig/include/linux/ipc.h 2008-01-11 15:50:21.000000000 +0100
+++ linux-2.6.24-rc7/include/linux/ipc.h 2008-01-11 16:00:50.000000000 +0100
@@ -121,6 +121,7 @@ struct ipc_namespace {
};

extern struct ipc_namespace init_ipc_ns;
+extern atomic_t nr_ipc_ns;

#ifdef CONFIG_SYSVIPC
#define INIT_IPC_NS(ns) .ns = &init_ipc_ns,
Index: linux-2.6.24-rc7/ipc/util.c
===================================================================
--- linux-2.6.24-rc7.orig/ipc/util.c 2008-01-11 15:50:21.000000000 +0100
+++ linux-2.6.24-rc7/ipc/util.c 2008-01-11 16:12:38.000000000 +0100
@@ -51,6 +51,9 @@ struct ipc_namespace init_ipc_ns = {
},
};

+atomic_t nr_ipc_ns = ATOMIC_INIT(1);
+
+
static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
{
int err;
@@ -61,6 +64,8 @@ static struct ipc_namespace *clone_ipc_n
if (ns == NULL)
goto err_mem;

+ atomic_inc(&nr_ipc_ns);
+
err = sem_init_ns(ns);
if (err)
goto err_sem;
@@ -80,6 +85,7 @@ err_msg:
sem_exit_ns(ns);
err_sem:
kfree(ns);
+ atomic_dec(&nr_ipc_ns);
err_mem:
return ERR_PTR(err);
}
@@ -109,6 +115,7 @@ void free_ipc_ns(struct kref *kref)
msg_exit_ns(ns);
shm_exit_ns(ns);
kfree(ns);
+ atomic_dec(&nr_ipc_ns);
}

/**
Index: linux-2.6.24-rc7/ipc/msg.c
===================================================================
--- linux-2.6.24-rc7.orig/ipc/msg.c 2008-01-11 15:51:00.000000000 +0100
+++ linux-2.6.24-rc7/ipc/msg.c 2008-01-11 16:08:32.000000000 +0100
@@ -83,15 +83,19 @@ static int sysvipc_msg_proc_show(struct
/*
* Scale msgmni with the available lowmem size: the memory dedicated to msg
* queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
+ * Also take into account the number of nsproxies created so far.
*/
static void recompute_msgmni(struct ipc_namespace *ns)
{
struct sysinfo i;
unsigned long allowed;
+ int nb_ns;

si_meminfo(&i);
allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
/ MSGMNB;
+ nb_ns = atomic_read(&nr_ipc_ns);
+ allowed /= nb_ns;

/*
* Never fall under the current minimum value
@@ -104,8 +108,8 @@ static void recompute_msgmni(struct ipc_
/*
* Never go over the current max value
*/
- if (allowed > IPCMNI) {
- ns->msg_ctlmni = IPCMNI;
+ if (allowed > IPCMNI / nb_ns) {
+ ns->msg_ctlmni = IPCMNI / nb_ns;
goto out_callback;
}

--