* [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames
@ 2015-08-05 6:54 Mike Looijmans
2015-08-14 7:53 ` Mike Looijmans
2015-09-03 9:36 ` Mike Looijmans
0 siblings, 2 replies; 4+ messages in thread
From: Mike Looijmans @ 2015-08-05 6:54 UTC (permalink / raw)
To: balbi, gregkh; +Cc: linux-usb, linux-kernel, Mike Looijmans
USB network adapters support Jumbo frames. The only thing blocking
that feature is the code in the gadget driver that disposes of
packets larger than 1518 bytes, and the limit on the ioctl to set
the mtu.
This patch relaxes these limits, and allows up to 15k frames sizes.
The 15k value was chosen because 16k does not work on all platforms,
and usingclose to 16k will result in allocating 5 or 8 4k pages to
store the skb, wasting pages at no measurable performance gain.
On a topic-miami board (Zynq-7000), iperf3 performance reports:
MTU= 1500, PC-to-gadget: 139 Mbps, Gadget-to-PC: 116 Mbps
MTU=15000, PC-to-gadget: 239 Mbps, Gadget-to-PC: 361 Mbps
On boards with slower CPUs the performance improvement will be
relatively much larger, e.g. an OMAP-L138 increased from 40 to
220 Mbps using a similar patch on an 2.6.37 kernel.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
---
drivers/usb/gadget/function/u_ether.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
index f1fd777..6828ea2 100644
--- a/drivers/usb/gadget/function/u_ether.c
+++ b/drivers/usb/gadget/function/u_ether.c
@@ -48,6 +48,11 @@
#define UETH__VERSION "29-May-2008"
+/* Experiments show that both Linux and Windows hosts allow up to 16k
+ * frame sizes. Set the max size to 15k+52 to prevent allocating 32k
+ * blocks and still have efficient handling. */
+#define GETHER_MAX_ETH_FRAME_LEN 15412
+
struct eth_dev {
/* lock is held while accessing port_usb
*/
@@ -146,7 +151,7 @@ static int ueth_change_mtu(struct net_device *net, int new_mtu)
spin_lock_irqsave(&dev->lock, flags);
if (dev->port_usb)
status = -EBUSY;
- else if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
+ else if (new_mtu <= ETH_HLEN || new_mtu > GETHER_MAX_ETH_FRAME_LEN)
status = -ERANGE;
else
net->mtu = new_mtu;
@@ -294,7 +299,7 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
while (skb2) {
if (status < 0
|| ETH_HLEN > skb2->len
- || skb2->len > VLAN_ETH_FRAME_LEN) {
+ || skb2->len > GETHER_MAX_ETH_FRAME_LEN) {
dev->net->stats.rx_errors++;
dev->net->stats.rx_length_errors++;
DBG(dev, "rx length %d\n", skb2->len);
--
1.9.1
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames
2015-08-05 6:54 [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames Mike Looijmans
@ 2015-08-14 7:53 ` Mike Looijmans
2015-09-03 9:36 ` Mike Looijmans
1 sibling, 0 replies; 4+ messages in thread
From: Mike Looijmans @ 2015-08-14 7:53 UTC (permalink / raw)
To: balbi, gregkh; +Cc: linux-usb, linux-kernel
ping...
More than a week has passed, haven't seen any response though. Any comments?
On 05-08-15 08:54, Mike Looijmans wrote:
> USB network adapters support Jumbo frames. The only thing blocking
> that feature is the code in the gadget driver that disposes of
> packets larger than 1518 bytes, and the limit on the ioctl to set
> the mtu.
>
> This patch relaxes these limits, and allows up to 15k frames sizes.
> The 15k value was chosen because 16k does not work on all platforms,
> and usingclose to 16k will result in allocating 5 or 8 4k pages to
> store the skb, wasting pages at no measurable performance gain.
>
> On a topic-miami board (Zynq-7000), iperf3 performance reports:
> MTU= 1500, PC-to-gadget: 139 Mbps, Gadget-to-PC: 116 Mbps
> MTU=15000, PC-to-gadget: 239 Mbps, Gadget-to-PC: 361 Mbps
>
> On boards with slower CPUs the performance improvement will be
> relatively much larger, e.g. an OMAP-L138 increased from 40 to
> 220 Mbps using a similar patch on an 2.6.37 kernel.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> ---
> drivers/usb/gadget/function/u_ether.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
> index f1fd777..6828ea2 100644
> --- a/drivers/usb/gadget/function/u_ether.c
> +++ b/drivers/usb/gadget/function/u_ether.c
> @@ -48,6 +48,11 @@
>
> #define UETH__VERSION "29-May-2008"
>
> +/* Experiments show that both Linux and Windows hosts allow up to 16k
> + * frame sizes. Set the max size to 15k+52 to prevent allocating 32k
> + * blocks and still have efficient handling. */
> +#define GETHER_MAX_ETH_FRAME_LEN 15412
> +
> struct eth_dev {
> /* lock is held while accessing port_usb
> */
> @@ -146,7 +151,7 @@ static int ueth_change_mtu(struct net_device *net, int new_mtu)
> spin_lock_irqsave(&dev->lock, flags);
> if (dev->port_usb)
> status = -EBUSY;
> - else if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
> + else if (new_mtu <= ETH_HLEN || new_mtu > GETHER_MAX_ETH_FRAME_LEN)
> status = -ERANGE;
> else
> net->mtu = new_mtu;
> @@ -294,7 +299,7 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
> while (skb2) {
> if (status < 0
> || ETH_HLEN > skb2->len
> - || skb2->len > VLAN_ETH_FRAME_LEN) {
> + || skb2->len > GETHER_MAX_ETH_FRAME_LEN) {
> dev->net->stats.rx_errors++;
> dev->net->stats.rx_length_errors++;
> DBG(dev, "rx length %d\n", skb2->len);
>
Kind regards,
Mike Looijmans
System Expert
TOPIC Embedded Products
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
Telefax: +31 (0) 499 33 69 70
E-mail: mike.looijmans@topicproducts.com
Website: www.topicproducts.com
Please consider the environment before printing this e-mail
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames
2015-08-05 6:54 [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames Mike Looijmans
2015-08-14 7:53 ` Mike Looijmans
@ 2015-09-03 9:36 ` Mike Looijmans
2015-09-03 14:25 ` Greg KH
1 sibling, 1 reply; 4+ messages in thread
From: Mike Looijmans @ 2015-09-03 9:36 UTC (permalink / raw)
To: balbi, gregkh; +Cc: linux-usb, linux-kernel
I'd like to bring this to your attention again please.
If there is something wrong about this patch, please tell me so.
And also note that this patch does not enable jumbo frames on itself, it just
removes the artificial limits in the kernel prohibiting mtus above 1500. The
MTU can be set from user space, and the impact on performance is quite impressive.
On 05-08-15 08:54, Mike Looijmans wrote:
> USB network adapters support Jumbo frames. The only thing blocking
> that feature is the code in the gadget driver that disposes of
> packets larger than 1518 bytes, and the limit on the ioctl to set
> the mtu.
>
> This patch relaxes these limits, and allows up to 15k frames sizes.
> The 15k value was chosen because 16k does not work on all platforms,
> and usingclose to 16k will result in allocating 5 or 8 4k pages to
> store the skb, wasting pages at no measurable performance gain.
>
> On a topic-miami board (Zynq-7000), iperf3 performance reports:
> MTU= 1500, PC-to-gadget: 139 Mbps, Gadget-to-PC: 116 Mbps
> MTU=15000, PC-to-gadget: 239 Mbps, Gadget-to-PC: 361 Mbps
>
> On boards with slower CPUs the performance improvement will be
> relatively much larger, e.g. an OMAP-L138 increased from 40 to
> 220 Mbps using a similar patch on an 2.6.37 kernel.
>
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> ---
> drivers/usb/gadget/function/u_ether.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
> index f1fd777..6828ea2 100644
> --- a/drivers/usb/gadget/function/u_ether.c
> +++ b/drivers/usb/gadget/function/u_ether.c
> @@ -48,6 +48,11 @@
>
> #define UETH__VERSION "29-May-2008"
>
> +/* Experiments show that both Linux and Windows hosts allow up to 16k
> + * frame sizes. Set the max size to 15k+52 to prevent allocating 32k
> + * blocks and still have efficient handling. */
> +#define GETHER_MAX_ETH_FRAME_LEN 15412
> +
> struct eth_dev {
> /* lock is held while accessing port_usb
> */
> @@ -146,7 +151,7 @@ static int ueth_change_mtu(struct net_device *net, int new_mtu)
> spin_lock_irqsave(&dev->lock, flags);
> if (dev->port_usb)
> status = -EBUSY;
> - else if (new_mtu <= ETH_HLEN || new_mtu > ETH_FRAME_LEN)
> + else if (new_mtu <= ETH_HLEN || new_mtu > GETHER_MAX_ETH_FRAME_LEN)
> status = -ERANGE;
> else
> net->mtu = new_mtu;
> @@ -294,7 +299,7 @@ static void rx_complete(struct usb_ep *ep, struct usb_request *req)
> while (skb2) {
> if (status < 0
> || ETH_HLEN > skb2->len
> - || skb2->len > VLAN_ETH_FRAME_LEN) {
> + || skb2->len > GETHER_MAX_ETH_FRAME_LEN) {
> dev->net->stats.rx_errors++;
> dev->net->stats.rx_length_errors++;
> DBG(dev, "rx length %d\n", skb2->len);
>
Kind regards,
Mike Looijmans
System Expert
TOPIC Embedded Products
Eindhovenseweg 32-C, NL-5683 KH Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
Telefax: +31 (0) 499 33 69 70
E-mail: mike.looijmans@topicproducts.com
Website: www.topicproducts.com
Please consider the environment before printing this e-mail
^ permalink raw reply [flat|nested] 4+ messages in thread
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2015-08-05 6:54 [PATCH] usb/gadget/function/u_ether.c: Allow jumbo frames Mike Looijmans
2015-08-14 7:53 ` Mike Looijmans
2015-09-03 9:36 ` Mike Looijmans
2015-09-03 14:25 ` Greg KH
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