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

[PATCH net-next] 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 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 24441ae..3960acd 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
 
-- 
1.7.1

[PATCH net-next] 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 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 24441ae..3960acd 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
 
-- 
1.7.1

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

[David Miller]

From: Haiyang Zhang <haiyangz@microsoft.com>
Date: Mon,  4 Aug 2014 12:33:45 -0700

> 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>

Now netvsc_device is significantly larger than a page, you should probably
therefore allocate netvsc_device->cb_buffer indirectly instead of inlining
it into the structure.

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

[Haiyang Zhang]

> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Monday, August 4, 2014 6:09 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] hyperv: Increase the buffer length for
> netvsc_channel_cb()
> 
> From: Haiyang Zhang <haiyangz@microsoft.com>
> Date: Mon,  4 Aug 2014 12:33:45 -0700
> 
> > 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>
> 
> Now netvsc_device is significantly larger than a page, you should probably
> therefore allocate netvsc_device->cb_buffer indirectly instead of inlining it into
> the structure.

I will make this update.
Thanks,
- Haiyang

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

[David Miller]

From: Haiyang Zhang <thomas1206@gmail.com>
Date: Fri,  1 Aug 2014 15:55:30 +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>

I'm not applying this, sorry.

I said that because the structure that contains this buffer is now
larger than a page, you should allocate the CB buffer externally
via another kmalloc() or via the page allocator.

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

[Haiyang Zhang]

> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Tuesday, August 5, 2014 4:04 PM
> To: thomas1206@gmail.com
> Cc: netdev@vger.kernel.org; Haiyang Zhang; KY Srinivasan; olaf@aepfle.de;
> jasowang@redhat.com; linux-kernel@vger.kernel.org; driverdev-
> devel@linuxdriverproject.org
> Subject: Re: [PATCH net-next] hyperv: Increase the buffer length for
> netvsc_channel_cb()
> 
> From: Haiyang Zhang <thomas1206@gmail.com>
> Date: Fri,  1 Aug 2014 15:55:30 +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>
> 
> I'm not applying this, sorry.
> 
> I said that because the structure that contains this buffer is now
> larger than a page, you should allocate the CB buffer externally
> via another kmalloc() or via the page allocator.

This must have been re-sent accidentally when we are updating our 
Email server... I will update the patch and re-submit it soon.

Thanks,
- Haiyang