rcu: remove useless ->boosted_this_gp field
Paul E. McKenney [Thu, 24 Feb 2011 23:25:21 +0000 (15:25 -0800)]
The ->boosted_this_gp field is a holdover from an earlier design that
was to carry out multiple boost operations in parallel.  It is not required
by the current design, which boosts one task at a time.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/rcutiny_plugin.h

index 0bc9f73..2b8d529 100644 (file)
@@ -100,7 +100,6 @@ struct rcu_preempt_ctrlblk {
        u8 completed;           /* Last grace period completed. */
                                /*  If all three are equal, RCU is idle. */
 #ifdef CONFIG_RCU_BOOST
-       s8 boosted_this_gp;     /* Has boosting already happened? */
        unsigned long boost_time; /* When to start boosting (jiffies) */
 #endif /* #ifdef CONFIG_RCU_BOOST */
 #ifdef CONFIG_RCU_TRACE
@@ -112,7 +111,6 @@ struct rcu_preempt_ctrlblk {
        unsigned long n_normal_balk_blkd_tasks;
        unsigned long n_normal_balk_gp_tasks;
        unsigned long n_normal_balk_boost_tasks;
-       unsigned long n_normal_balk_boosted;
        unsigned long n_normal_balk_notyet;
        unsigned long n_normal_balk_nos;
        unsigned long n_exp_balk_blkd_tasks;
@@ -219,36 +217,19 @@ static void show_tiny_preempt_stats(struct seq_file *m)
                   "N."[!rcu_preempt_ctrlblk.gp_tasks],
                   "E."[!rcu_preempt_ctrlblk.exp_tasks]);
 #ifdef CONFIG_RCU_BOOST
-       seq_printf(m, "             ttb=%c btg=",
-                  "B."[!rcu_preempt_ctrlblk.boost_tasks]);
-       switch (rcu_preempt_ctrlblk.boosted_this_gp) {
-       case -1:
-               seq_puts(m, "exp");
-               break;
-       case 0:
-               seq_puts(m, "no");
-               break;
-       case 1:
-               seq_puts(m, "begun");
-               break;
-       case 2:
-               seq_puts(m, "done");
-               break;
-       default:
-               seq_printf(m, "?%d?", rcu_preempt_ctrlblk.boosted_this_gp);
-       }
-       seq_printf(m, " ntb=%lu neb=%lu nnb=%lu j=%04x bt=%04x\n",
+       seq_printf(m, "%sttb=%c ntb=%lu neb=%lu nnb=%lu j=%04x bt=%04x\n",
+                  "             ",
+                  "B."[!rcu_preempt_ctrlblk.boost_tasks],
                   rcu_preempt_ctrlblk.n_tasks_boosted,
                   rcu_preempt_ctrlblk.n_exp_boosts,
                   rcu_preempt_ctrlblk.n_normal_boosts,
                   (int)(jiffies & 0xffff),
                   (int)(rcu_preempt_ctrlblk.boost_time & 0xffff));
-       seq_printf(m, "             %s: nt=%lu gt=%lu bt=%lu b=%lu ny=%lu nos=%lu\n",
+       seq_printf(m, "             %s: nt=%lu gt=%lu bt=%lu ny=%lu nos=%lu\n",
                   "normal balk",
                   rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks,
                   rcu_preempt_ctrlblk.n_normal_balk_gp_tasks,
                   rcu_preempt_ctrlblk.n_normal_balk_boost_tasks,
-                  rcu_preempt_ctrlblk.n_normal_balk_boosted,
                   rcu_preempt_ctrlblk.n_normal_balk_notyet,
                   rcu_preempt_ctrlblk.n_normal_balk_nos);
        seq_printf(m, "             exp balk: bt=%lu nos=%lu\n",
@@ -277,7 +258,6 @@ static int rcu_boost(void)
        if (rcu_preempt_ctrlblk.boost_tasks == NULL)
                return 0;  /* Nothing to boost. */
        raw_local_irq_save(flags);
-       rcu_preempt_ctrlblk.boosted_this_gp++;
        t = container_of(rcu_preempt_ctrlblk.boost_tasks, struct task_struct,
                         rcu_node_entry);
        np = rcu_next_node_entry(t);
@@ -287,7 +267,6 @@ static int rcu_boost(void)
        raw_local_irq_restore(flags);
        rt_mutex_lock(&mtx);
        RCU_TRACE(rcu_preempt_ctrlblk.n_tasks_boosted++);
-       rcu_preempt_ctrlblk.boosted_this_gp++;
        rt_mutex_unlock(&mtx);
        return rcu_preempt_ctrlblk.boost_tasks != NULL;
 }
@@ -310,7 +289,6 @@ static int rcu_initiate_boost(void)
        }
        if (rcu_preempt_ctrlblk.gp_tasks != NULL &&
            rcu_preempt_ctrlblk.boost_tasks == NULL &&
-           rcu_preempt_ctrlblk.boosted_this_gp == 0 &&
            ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time)) {
                rcu_preempt_ctrlblk.boost_tasks = rcu_preempt_ctrlblk.gp_tasks;
                invoke_rcu_kthread();
@@ -331,7 +309,6 @@ static void rcu_initiate_expedited_boost(void)
        if (!list_empty(&rcu_preempt_ctrlblk.blkd_tasks)) {
                rcu_preempt_ctrlblk.boost_tasks =
                        rcu_preempt_ctrlblk.blkd_tasks.next;
-               rcu_preempt_ctrlblk.boosted_this_gp = -1;
                invoke_rcu_kthread();
                RCU_TRACE(rcu_preempt_ctrlblk.n_exp_boosts++);
        } else
@@ -347,8 +324,6 @@ static void rcu_initiate_expedited_boost(void)
 static void rcu_preempt_boost_start_gp(void)
 {
        rcu_preempt_ctrlblk.boost_time = jiffies + RCU_BOOST_DELAY_JIFFIES;
-       if (rcu_preempt_ctrlblk.boosted_this_gp > 0)
-               rcu_preempt_ctrlblk.boosted_this_gp = 0;
 }
 
 #else /* #ifdef CONFIG_RCU_BOOST */
@@ -934,8 +909,6 @@ static void rcu_initiate_boost_trace(void)
                rcu_preempt_ctrlblk.n_normal_balk_gp_tasks++;
        else if (rcu_preempt_ctrlblk.boost_tasks != NULL)
                rcu_preempt_ctrlblk.n_normal_balk_boost_tasks++;
-       else if (rcu_preempt_ctrlblk.boosted_this_gp != 0)
-               rcu_preempt_ctrlblk.n_normal_balk_boosted++;
        else if (!ULONG_CMP_GE(jiffies, rcu_preempt_ctrlblk.boost_time))
                rcu_preempt_ctrlblk.n_normal_balk_notyet++;
        else