nfs: new subdir Documentation/filesystems/nfs

[safe/jmp/linux-2.6] / block / blk-iopoll.c

diff --git a/block/blk-iopoll.c b/block/blk-iopoll.c
index 566db1e..ca56420 100644 (file)
--- a/block/blk-iopoll.c
+++ b/block/blk-iopoll.c
@@ -17,6 +17,8 @@
 int blk_iopoll_enabled = 1;
 EXPORT_SYMBOL(blk_iopoll_enabled);
 
+static unsigned int blk_iopoll_budget __read_mostly = 256;
+
 static DEFINE_PER_CPU(struct list_head, blk_cpu_iopoll);
 
 /**
@@ -24,9 +26,9 @@ static DEFINE_PER_CPU(struct list_head, blk_cpu_iopoll);
  * @iop:      The parent iopoll structure
  *
  * Description:
- *     Add this blk_iopoll structure to the pending poll list and trigger the raise
- *     of the blk iopoll softirq. The driver must already have gotten a succesful
- *     return from blk_iopoll_sched_prep() before calling this.
+ *     Add this blk_iopoll structure to the pending poll list and trigger the
+ *     raise of the blk iopoll softirq. The driver must already have gotten a
+ *     succesful return from blk_iopoll_sched_prep() before calling this.
  **/
 void blk_iopoll_sched(struct blk_iopoll *iop)
 {
@@ -44,7 +46,8 @@ EXPORT_SYMBOL(blk_iopoll_sched);
  * @iop:      The parent iopoll structure
  *
  * Description:
- *     See blk_iopoll_complete(). This function must be called with interrupts disabled.
+ *     See blk_iopoll_complete(). This function must be called with interrupts
+ *     disabled.
  **/
 void __blk_iopoll_complete(struct blk_iopoll *iop)
 {
@@ -59,9 +62,10 @@ EXPORT_SYMBOL(__blk_iopoll_complete);
  * @iop:      The parent iopoll structure
  *
  * Description:
- *     If a driver consumes less than the assigned budget in its run of the iopoll
- *     handler, it'll end the polled mode by calling this function. The iopoll handler
- *     will not be invoked again before blk_iopoll_sched_prep() is called.
+ *     If a driver consumes less than the assigned budget in its run of the
+ *     iopoll handler, it'll end the polled mode by calling this function. The
+ *     iopoll handler will not be invoked again before blk_iopoll_sched_prep()
+ *     is called.
  **/
 void blk_iopoll_complete(struct blk_iopoll *iopoll)
 {
@@ -76,8 +80,8 @@ EXPORT_SYMBOL(blk_iopoll_complete);
 static void blk_iopoll_softirq(struct softirq_action *h)
 {
        struct list_head *list = &__get_cpu_var(blk_cpu_iopoll);
+       int rearm = 0, budget = blk_iopoll_budget;
        unsigned long start_time = jiffies;
-       int rearm = 0, budget = 64;
 
        local_irq_disable();
 
@@ -111,9 +115,12 @@ static void blk_iopoll_softirq(struct softirq_action *h)
 
                local_irq_disable();
 
-               /* Drivers must not modify the NAPI state if they
-                * consume the entire weight.  In such cases this code
-                * still "owns" the NAPI instance and therefore can
+               /*
+                * Drivers must not modify the iopoll state, if they
+                * consume their assigned weight (or more, some drivers can't
+                * easily just stop processing, they have to complete an
+                * entire mask of commands).In such cases this code
+                * still "owns" the iopoll instance and therefore can
                 * move the instance around on the list at-will.
                 */
                if (work >= weight) {
@@ -151,13 +158,13 @@ EXPORT_SYMBOL(blk_iopoll_disable);
  * @iop:      The parent iopoll structure
  *
  * Description:
- *     Enable iopoll on this @iop. Note that the handler run will not be scheduled, it
- *     will only mark it as active.
+ *     Enable iopoll on this @iop. Note that the handler run will not be
+ *     scheduled, it will only mark it as active.
  **/
 void blk_iopoll_enable(struct blk_iopoll *iop)
 {
        BUG_ON(!test_bit(IOPOLL_F_SCHED, &iop->state));
-        smp_mb__before_clear_bit();
+       smp_mb__before_clear_bit();
        clear_bit_unlock(IOPOLL_F_SCHED, &iop->state);
 }
 EXPORT_SYMBOL(blk_iopoll_enable);
@@ -169,8 +176,8 @@ EXPORT_SYMBOL(blk_iopoll_enable);
  * @poll_fn:  The handler to invoke
  *
  * Description:
- *     Initialize this blk_iopoll structure. Before being actively used, the driver
- *     must call blk_iopoll_enable().
+ *     Initialize this blk_iopoll structure. Before being actively used, the
+ *     driver must call blk_iopoll_enable().
  **/
 void blk_iopoll_init(struct blk_iopoll *iop, int weight, blk_iopoll_fn *poll_fn)
 {
@@ -195,7 +202,7 @@ static int __cpuinit blk_iopoll_cpu_notify(struct notifier_block *self,
                local_irq_disable();
                list_splice_init(&per_cpu(blk_cpu_iopoll, cpu),
                                 &__get_cpu_var(blk_cpu_iopoll));
-               raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ);
+               __raise_softirq_irqoff(BLOCK_IOPOLL_SOFTIRQ);
                local_irq_enable();
        }