2 files changed, 130 insertions, 19 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 03eb5ed503f7..6e92ba61f7c0 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1685,6 +1685,22 @@ and is between 256 and 4096 characters. It is defined in the file
         stifb=          [HW]
                         Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
 
+        sunrpc.pool_mode=
+                        [NFS]
+                        Control how the NFS server code allocates CPUs to
+                        service thread pools.  Depending on how many NICs
+                        you have and where their interrupts are bound, this
+                        option will affect which CPUs will do NFS serving.
+                        Note: this parameter cannot be changed while the
+                        NFS server is running.
+
+                        auto        the server chooses an appropriate mode
+                                    automatically using heuristics
+                        global      a single global pool contains all CPUs
+                        percpu      one pool for each CPU
+                        pernode     one pool for each NUMA node (equivalent
+                                    to global on non-NUMA machines)
+
         swiotlb=        [IA-64] Number of I/O TLB slabs
 
         switches=       [HW,M68k]
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
index f960b138236f..b4db53ff1435 100644
--- a/net/sunrpc/svc.c
+++ b/net/sunrpc/svc.c
@@ -27,22 +27,26 @@
 
 #define RPCDBG_FACILITY RPCDBG_SVCDSP
 
+#define svc_serv_is_pooled(serv)    ((serv)->sv_function)
+
 /*
  * Mode for mapping cpus to pools.
  */
 enum {
-        SVC_POOL_NONE = -1,     /* uninitialised, choose one of the others */
+        SVC_POOL_AUTO = -1,     /* choose one of the others */
         SVC_POOL_GLOBAL,        /* no mapping, just a single global pool
                                  * (legacy & UP mode) */
         SVC_POOL_PERCPU,        /* one pool per cpu */
         SVC_POOL_PERNODE        /* one pool per numa node */
 };
+#define SVC_POOL_DEFAULT        SVC_POOL_GLOBAL
 
 /*
  * Structure for mapping cpus to pools and vice versa.
  * Setup once during sunrpc initialisation.
  */
 static struct svc_pool_map {
+        int count;                      /* How many svc_servs use us */
         int mode;                       /* Note: int not enum to avoid
                                          * warnings about "enumeration value
                                          * not handled in switch" */
@@ -50,9 +54,63 @@ static struct svc_pool_map {
         unsigned int *pool_to;          /* maps pool id to cpu or node */
         unsigned int *to_pool;          /* maps cpu or node to pool id */
 } svc_pool_map = {
-        .mode = SVC_POOL_NONE
+        .count = 0,
+        .mode = SVC_POOL_DEFAULT
 };
+static DEFINE_MUTEX(svc_pool_map_mutex);/* protects svc_pool_map.count only */
+
+static int
+param_set_pool_mode(const char *val, struct kernel_param *kp)
+{
+        int *ip = (int *)kp->arg;
+        struct svc_pool_map *m = &svc_pool_map;
+        int err;
+
+        mutex_lock(&svc_pool_map_mutex);
+
+        err = -EBUSY;
+        if (m->count)
+                goto out;
+
+        err = 0;
+        if (!strncmp(val, "auto", 4))
+                *ip = SVC_POOL_AUTO;
+        else if (!strncmp(val, "global", 6))
+                *ip = SVC_POOL_GLOBAL;
+        else if (!strncmp(val, "percpu", 6))
+                *ip = SVC_POOL_PERCPU;
+        else if (!strncmp(val, "pernode", 7))
+                *ip = SVC_POOL_PERNODE;
+        else
+                err = -EINVAL;
+
+out:
+        mutex_unlock(&svc_pool_map_mutex);
+        return err;
+}
+
+static int
+param_get_pool_mode(char *buf, struct kernel_param *kp)
+{
+        int *ip = (int *)kp->arg;
+
+        switch (*ip)
+        {
+        case SVC_POOL_AUTO:
+                return strlcpy(buf, "auto", 20);
+        case SVC_POOL_GLOBAL:
+                return strlcpy(buf, "global", 20);
+        case SVC_POOL_PERCPU:
+                return strlcpy(buf, "percpu", 20);
+        case SVC_POOL_PERNODE:
+                return strlcpy(buf, "pernode", 20);
+        default:
+                return sprintf(buf, "%d", *ip);
+        }
+}
 
+module_param_call(pool_mode, param_set_pool_mode, param_get_pool_mode,
+                 &svc_pool_map.mode, 0644);
 
 /*
  * Detect best pool mapping mode heuristically,
@@ -166,18 +224,25 @@ svc_pool_map_init_pernode(struct svc_pool_map *m)
 
 
 /*
- * Build the global map of cpus to pools and vice versa.
+ * Add a reference to the global map of cpus to pools (and
+ * vice versa).  Initialise the map if we're the first user.
+ * Returns the number of pools.
  */
 static unsigned int
-svc_pool_map_init(void)
+svc_pool_map_get(void)
 {
         struct svc_pool_map *m = &svc_pool_map;
         int npools = -1;
 
-        if (m->mode != SVC_POOL_NONE)
+        mutex_lock(&svc_pool_map_mutex);
+
+        if (m->count++) {
+                mutex_unlock(&svc_pool_map_mutex);
                 return m->npools;
+        }
 
-        m->mode = svc_pool_map_choose_mode();
+        if (m->mode == SVC_POOL_AUTO)
+                m->mode = svc_pool_map_choose_mode();
 
         switch (m->mode) {
         case SVC_POOL_PERCPU:
@@ -195,9 +260,36 @@ svc_pool_map_init(void)
         }
         m->npools = npools;
 
+        mutex_unlock(&svc_pool_map_mutex);
         return m->npools;
 }
 
+
+/*
+ * Drop a reference to the global map of cpus to pools.
+ * When the last reference is dropped, the map data is
+ * freed; this allows the sysadmin to change the pool
+ * mode using the pool_mode module option without
+ * rebooting or re-loading sunrpc.ko.
+ */
+static void
+svc_pool_map_put(void)
+{
+        struct svc_pool_map *m = &svc_pool_map;
+
+        mutex_lock(&svc_pool_map_mutex);
+
+        if (!--m->count) {
+                m->mode = SVC_POOL_DEFAULT;
+                kfree(m->to_pool);
+                kfree(m->pool_to);
+                m->npools = 0;
+        }
+
+        mutex_unlock(&svc_pool_map_mutex);
+}
+
+
 /*
  * Set the current thread's cpus_allowed mask so that it
  * will only run on cpus in the given pool.
@@ -212,10 +304,9 @@ svc_pool_map_set_cpumask(unsigned int pidx, cpumask_t *oldmask)
 
         /*
          * The caller checks for sv_nrpools > 1, which
-         * implies that we've been initialized and the
-         * map mode is not NONE.
+         * implies that we've been initialized.
          */
-        BUG_ON(m->mode == SVC_POOL_NONE);
+        BUG_ON(m->count == 0);
 
         switch (m->mode)
         {
@@ -246,18 +337,19 @@ svc_pool_for_cpu(struct svc_serv *serv, int cpu)
         unsigned int pidx = 0;
 
         /*
-         * SVC_POOL_NONE happens in a pure client when
+         * An uninitialised map happens in a pure client when
          * lockd is brought up, so silently treat it the
          * same as SVC_POOL_GLOBAL.
          */
-
-        switch (m->mode) {
-        case SVC_POOL_PERCPU:
-                pidx = m->to_pool[cpu];
-                break;
-        case SVC_POOL_PERNODE:
-                pidx = m->to_pool[cpu_to_node(cpu)];
-                break;
+        if (svc_serv_is_pooled(serv)) {
+                switch (m->mode) {
+                case SVC_POOL_PERCPU:
+                        pidx = m->to_pool[cpu];
+                        break;
+                case SVC_POOL_PERNODE:
+                        pidx = m->to_pool[cpu_to_node(cpu)];
+                        break;
+                }
         }
         return &serv->sv_pools[pidx % serv->sv_nrpools];
 }
@@ -347,7 +439,7 @@ svc_create_pooled(struct svc_program *prog, unsigned int bufsize,
                   svc_thread_fn func, int sig, struct module *mod)
 {
         struct svc_serv *serv;
-        unsigned int npools = svc_pool_map_init();
+        unsigned int npools = svc_pool_map_get();
 
         serv = __svc_create(prog, bufsize, npools, shutdown);
 
@@ -397,6 +489,9 @@ svc_destroy(struct svc_serv *serv)
 
         cache_clean_deferred(serv);
 
+        if (svc_serv_is_pooled(serv))
+                svc_pool_map_put();
+
         /* Unregister service with the portmapper */
         svc_register(serv, 0, 0);
         kfree(serv->sv_pools);