[PATCH net-next, v2] hyperv: Increase the buffer length for netvsc_channel_cb()

[PATCH net-next, v2] hyperv: Increase the buffer length for netvsc_channel_cb()

[Haiyang Zhang]

When the buffer is too small for a packet from VMBus, a bigger buffer will be
allocated in netvsc_channel_cb() and retry reading the packet from VMBus.
Increasing this buffer size will reduce the retry overhead.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h |    2 +-
 drivers/net/hyperv/netvsc.c     |    6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index d5e07de..b14a0ef 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -591,7 +591,7 @@ struct nvsp_message {
 
 #define NETVSC_RECEIVE_BUFFER_ID		0xcafe
 
-#define NETVSC_PACKET_SIZE                      2048
+#define NETVSC_PACKET_SIZE                      4096
 
 #define VRSS_SEND_TAB_SIZE 16
 
diff --git a/drivers/net/hyperv/netvsc.c b/drivers/net/hyperv/netvsc.c
index 66979cf..45899f2 100644
--- a/drivers/net/hyperv/netvsc.c
+++ b/drivers/net/hyperv/netvsc.c
@@ -38,7 +38,7 @@ static struct netvsc_device *alloc_net_device(struct hv_device *device)
 	struct netvsc_device *net_device;
 	struct net_device *ndev = hv_get_drvdata(device);
 
-	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
+	net_device = vzalloc(sizeof(*net_device));
 	if (!net_device)
 		return NULL;
 
@@ -551,7 +551,7 @@ int netvsc_device_remove(struct hv_device *device)
 	if (net_device->sub_cb_buf)
 		vfree(net_device->sub_cb_buf);
 
-	kfree(net_device);
+	vfree(net_device);
 	return 0;
 }
 
@@ -1093,7 +1093,7 @@ close:
 	vmbus_close(device->channel);
 
 cleanup:
-	kfree(net_device);
+	vfree(net_device);
 
 	return ret;
 }
-- 
1.7.1

Re: [PATCH net-next,v2] hyperv: Increase the buffer length for netvsc_channel_cb()

[David Miller]

From: Haiyang Zhang <haiyangz@microsoft.com>
Date: Wed, 13 Aug 2014 18:03:44 +0000

> When the buffer is too small for a packet from VMBus, a bigger buffer will be
> allocated in netvsc_channel_cb() and retry reading the packet from VMBus.
> Increasing this buffer size will reduce the retry overhead.
> 
> Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> Reviewed-by: Dexuan Cui <decui@microsoft.com>
...
> -	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
> +	net_device = vzalloc(sizeof(*net_device));

This isn't what I suggested that you do.

I said that the buffer inside of netvsc_device should be made an
indirect pointer and thus allocated seperately.

Thus you're still kzalloc() net_device, but net_device->cb_buffer
becomes "unsigned char *" and another allocation is made for it.

RE: [PATCH net-next,v2] hyperv: Increase the buffer length for netvsc_channel_cb()

[Haiyang Zhang]

> -----Original Message-----
> From: David Miller [mailto:davem@redhat.com]
> Sent: Thursday, August 14, 2014 5:29 PM
> To: Haiyang Zhang
> Cc: netdev@vger.kernel.org; KY Srinivasan; olaf@aepfle.de;
> jasowang@redhat.com; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org
> Subject: Re: [PATCH net-next,v2] hyperv: Increase the buffer length for
> netvsc_channel_cb()
> 
> From: Haiyang Zhang <haiyangz@microsoft.com>
> Date: Wed, 13 Aug 2014 18:03:44 +0000
> 
> > When the buffer is too small for a packet from VMBus, a bigger buffer
> will be
> > allocated in netvsc_channel_cb() and retry reading the packet from
> VMBus.
> > Increasing this buffer size will reduce the retry overhead.
> >
> > Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
> > Reviewed-by: Dexuan Cui <decui@microsoft.com>
> ...
> > -	net_device = kzalloc(sizeof(struct netvsc_device), GFP_KERNEL);
> > +	net_device = vzalloc(sizeof(*net_device));
> 
> This isn't what I suggested that you do.
> 
> I said that the buffer inside of netvsc_device should be made an
> indirect pointer and thus allocated seperately.
> 
> Thus you're still kzalloc() net_device, but net_device->cb_buffer
> becomes "unsigned char *" and another allocation is made for it.

I will change the patch to this way.
Thanks,

- Haiyang