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[PATCH net-next V3 0/6] switch to use tx skb array in tun

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  [PATCH net-next V3 0/6] switch to use tx skb array in tun Jason Wang <jasowang@redhat.com> - 2016-06-30 06:10 +0200
    [PATCH net-next V3 3/6] ptr_ring: support resizing multiple queues Jason Wang <jasowang@redhat.com> - 2016-06-30 06:10 +0200
    Re: [PATCH net-next V3 0/6] switch to use tx skb array in tun "Michael S. Tsirkin" <mst@redhat.com> - 2016-06-30 07:40 +0200

#1434215 — [PATCH net-next V3 0/6] switch to use tx skb array in tun

Hi all:

This series tries to switch to use skb array in tun. This is used to
eliminate the spinlock contention between producer and consumer. The
conversion was straightforward: just introdce a tx skb array and use
it instead of sk_receive_queue.

A minor issue is to keep the tx_queue_len behaviour, since tun used to
use it for the length of sk_receive_queue. This is done through:

- add the ability to resize multiple rings at once to avoid handling
  partial resize failure for mutiple rings.
- add the support for zero length ring.
- introduce a notifier which was triggered when tx_queue_len was
  changed for a netdev.
- resize all queues during the tx_queue_len changing.

Tests shows about 15% improvement on guest rx pps:

Before: ~1300000pps
After : ~1500000pps

Changes from V2:
- add multiple rings resizing support for ptr_ring/skb_array
- add zero length ring support
- introdce a NETDEV_CHANGE_TX_QUEUE_LEN
- drop new flags

Changes from V1:
- switch to use skb array instead of a customized circular buffer
- add non-blocking support
- rename .peek to .peek_len
- drop lockless peeking since test show very minor improvement

Jason Wang (5):
  ptr_ring: support zero length ring
  skb_array: minor tweak
  skb_array: add wrappers for resizing
  net: introduce NETDEV_CHANGE_TX_QUEUE_LEN
  tun: switch to use skb array for tx

Michael S. Tsirkin (1):
  ptr_ring: support resizing multiple queues

 drivers/net/tun.c                | 138 ++++++++++++++++++++++++++++++++++++---
 drivers/vhost/net.c              |  16 ++++-
 include/linux/net.h              |   1 +
 include/linux/netdevice.h        |   1 +
 include/linux/ptr_ring.h         |  77 ++++++++++++++++++----
 include/linux/skb_array.h        |  13 +++-
 net/core/net-sysfs.c             |  15 ++++-
 tools/virtio/ringtest/ptr_ring.c |   5 ++
 8 files changed, 243 insertions(+), 23 deletions(-)

-- 
2.7.4

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#1434216 — [PATCH net-next V3 3/6] ptr_ring: support resizing multiple queues

From: "Michael S. Tsirkin" <mst@redhat.com>

Sometimes, we need support resizing multiple queues at once. This is
because it was not easy to recover to recover from a partial failure
of multiple queues resizing.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 include/linux/ptr_ring.h         | 71 +++++++++++++++++++++++++++++++++++-----
 tools/virtio/ringtest/ptr_ring.c |  5 +++
 2 files changed, 67 insertions(+), 9 deletions(-)

diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h
index d78b8b8..2052011 100644
--- a/include/linux/ptr_ring.h
+++ b/include/linux/ptr_ring.h
@@ -349,20 +349,14 @@ static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
 	return 0;
 }
 
-static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
-				  void (*destroy)(void *))
+static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
+					   int size, gfp_t gfp,
+					   void (*destroy)(void *))
 {
-	unsigned long flags;
 	int producer = 0;
-	void **queue = __ptr_ring_init_queue_alloc(size, gfp);
 	void **old;
 	void *ptr;
 
-	if (!queue)
-		return -ENOMEM;
-
-	spin_lock_irqsave(&(r)->producer_lock, flags);
-
 	while ((ptr = ptr_ring_consume(r)))
 		if (producer < size)
 			queue[producer++] = ptr;
@@ -375,6 +369,23 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
 	old = r->queue;
 	r->queue = queue;
 
+	return old;
+}
+
+static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
+				  void (*destroy)(void *))
+{
+	unsigned long flags;
+	void **queue = __ptr_ring_init_queue_alloc(size, gfp);
+	void **old;
+
+	if (!queue)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&(r)->producer_lock, flags);
+
+	old = __ptr_ring_swap_queue(r, queue, size, gfp, destroy);
+
 	spin_unlock_irqrestore(&(r)->producer_lock, flags);
 
 	kfree(old);
@@ -382,6 +393,48 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
 	return 0;
 }
 
+static inline int ptr_ring_resize_multiple(struct ptr_ring **rings, int nrings,
+					   int size,
+					   gfp_t gfp, void (*destroy)(void *))
+{
+	unsigned long flags;
+	void ***queues;
+	int i;
+
+	queues = kmalloc(nrings * sizeof *queues, gfp);
+	if (!queues)
+		goto noqueues;
+
+	for (i = 0; i < nrings; ++i) {
+		queues[i] = __ptr_ring_init_queue_alloc(size, gfp);
+		if (!queues[i])
+			goto nomem;
+	}
+
+	for (i = 0; i < nrings; ++i) {
+		spin_lock_irqsave(&(rings[i])->producer_lock, flags);
+		queues[i] = __ptr_ring_swap_queue(rings[i], queues[i],
+						  size, gfp, destroy);
+		spin_unlock_irqrestore(&(rings[i])->producer_lock, flags);
+	}
+
+	for (i = 0; i < nrings; ++i)
+		kfree(queues[i]);
+
+	kfree(queues);
+
+	return 0;
+
+nomem:
+	while (--i >= 0)
+		kfree(queues[i]);
+
+	kfree(queues);
+
+noqueues:
+	return -ENOMEM;
+}
+
 static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
 {
 	void *ptr;
diff --git a/tools/virtio/ringtest/ptr_ring.c b/tools/virtio/ringtest/ptr_ring.c
index 74abd74..68e4f9f 100644
--- a/tools/virtio/ringtest/ptr_ring.c
+++ b/tools/virtio/ringtest/ptr_ring.c
@@ -17,6 +17,11 @@
 typedef pthread_spinlock_t  spinlock_t;
 
 typedef int gfp_t;
+static void *kmalloc(unsigned size, gfp_t gfp)
+{
+	return memalign(64, size);
+}
+
 static void *kzalloc(unsigned size, gfp_t gfp)
 {
 	void *p = memalign(64, size);
-- 
2.7.4

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#1434230

On Thu, Jun 30, 2016 at 11:52:53AM +0800, Jason Wang wrote:
> Hi all:
> 
> This series tries to switch to use skb array in tun. This is used to
> eliminate the spinlock contention between producer and consumer. The
> conversion was straightforward: just introdce a tx skb array and use
> it instead of sk_receive_queue.
> 
> A minor issue is to keep the tx_queue_len behaviour, since tun used to
> use it for the length of sk_receive_queue. This is done through:
> 
> - add the ability to resize multiple rings at once to avoid handling
>   partial resize failure for mutiple rings.
> - add the support for zero length ring.
> - introduce a notifier which was triggered when tx_queue_len was
>   changed for a netdev.
> - resize all queues during the tx_queue_len changing.
> 
> Tests shows about 15% improvement on guest rx pps:
> 
> Before: ~1300000pps
> After : ~1500000pps

Series:

Acked-by: Michael S. Tsirkin <mst@redhat.com>


> Changes from V2:
> - add multiple rings resizing support for ptr_ring/skb_array
> - add zero length ring support
> - introdce a NETDEV_CHANGE_TX_QUEUE_LEN
> - drop new flags
> 
> Changes from V1:
> - switch to use skb array instead of a customized circular buffer
> - add non-blocking support
> - rename .peek to .peek_len
> - drop lockless peeking since test show very minor improvement
> 
> Jason Wang (5):
>   ptr_ring: support zero length ring
>   skb_array: minor tweak
>   skb_array: add wrappers for resizing
>   net: introduce NETDEV_CHANGE_TX_QUEUE_LEN
>   tun: switch to use skb array for tx
> 
> Michael S. Tsirkin (1):
>   ptr_ring: support resizing multiple queues
> 
>  drivers/net/tun.c                | 138 ++++++++++++++++++++++++++++++++++++---
>  drivers/vhost/net.c              |  16 ++++-
>  include/linux/net.h              |   1 +
>  include/linux/netdevice.h        |   1 +
>  include/linux/ptr_ring.h         |  77 ++++++++++++++++++----
>  include/linux/skb_array.h        |  13 +++-
>  net/core/net-sysfs.c             |  15 ++++-
>  tools/virtio/ringtest/ptr_ring.c |   5 ++
>  8 files changed, 243 insertions(+), 23 deletions(-)
> 
> -- 
> 2.7.4

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