Re: [PATCH net-next 1/8] ptr_ring: introduce batch dequeuing
From: Jason Wang
Date: Thu Mar 23 2017 - 04:02:08 EST
On 2017å03æ22æ 21:43, Michael S. Tsirkin wrote:
On Tue, Mar 21, 2017 at 12:04:40PM +0800, Jason Wang wrote:
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
include/linux/ptr_ring.h | 65 ++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index 6c70444..4771ded 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -247,6 +247,22 @@ static inline void *__ptr_ring_consume(struct ptr_ring *r)
return ptr;
}
+static inline int __ptr_ring_consume_batched(struct ptr_ring *r,
+ void **array, int n)
+{
+ void *ptr;
+ int i = 0;
+
+ while (i < n) {
+ ptr = __ptr_ring_consume(r);
+ if (!ptr)
+ break;
+ array[i++] = ptr;
+ }
+
+ return i;
+}
+
/*
* Note: resize (below) nests producer lock within consumer lock, so if you
* call this in interrupt or BH context, you must disable interrupts/BH when
This ignores the comment above that function:
/* Note: callers invoking this in a loop must use a compiler barrier,
* for example cpu_relax().
*/
Yes, __ptr_ring_swap_queue() ignores this too.
Also - it looks like it shouldn't matter if reads are reordered but I wonder.
Thoughts? Including some reasoning about it in commit log would be nice.
Yes, I think it doesn't matter in this case, it matters only for batched
producing.
Thanks
@@ -297,6 +313,55 @@ static inline void *ptr_ring_consume_bh(struct ptr_ring *r)
return ptr;
}
+static inline int ptr_ring_consume_batched(struct ptr_ring *r,
+ void **array, int n)
+{
+ int ret;
+
+ spin_lock(&r->consumer_lock);
+ ret = __ptr_ring_consume_batched(r, array, n);
+ spin_unlock(&r->consumer_lock);
+
+ return ret;
+}
+
+static inline int ptr_ring_consume_batched_irq(struct ptr_ring *r,
+ void **array, int n)
+{
+ int ret;
+
+ spin_lock_irq(&r->consumer_lock);
+ ret = __ptr_ring_consume_batched(r, array, n);
+ spin_unlock_irq(&r->consumer_lock);
+
+ return ret;
+}
+
+static inline int ptr_ring_consume_batched_any(struct ptr_ring *r,
+ void **array, int n)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&r->consumer_lock, flags);
+ ret = __ptr_ring_consume_batched(r, array, n);
+ spin_unlock_irqrestore(&r->consumer_lock, flags);
+
+ return ret;
+}
+
+static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
+ void **array, int n)
+{
+ int ret;
+
+ spin_lock_bh(&r->consumer_lock);
+ ret = __ptr_ring_consume_batched(r, array, n);
+ spin_unlock_bh(&r->consumer_lock);
+
+ return ret;
+}
+
/* Cast to structure type and call a function without discarding from FIFO.
* Function must return a value.
* Callers must take consumer_lock.
--
2.7.4