On 22. 12. 21. 15:32, Greg KH wrote:
On Wed, Dec 21, 2022 at 01:42:30PM +0900, Leesoo Ahn wrote:
The current source pushes skb into dev->done queue by calling
skb_queue_tail() and then pop it by calling skb_dequeue() to branch to
rx_cleanup state for freeing urb/skb in usbnet_bh(). It takes extra CPU
load, 2.21% (skb_queue_tail) as follows.
- 11.58% 0.26% swapper [k] usbnet_bh
- 11.32% usbnet_bh
- 6.43% skb_dequeue
6.34% _raw_spin_unlock_irqrestore
- 2.21% skb_queue_tail
2.19% _raw_spin_unlock_irqrestore
- 1.68% consume_skb
- 0.97% kfree_skbmem
0.80% kmem_cache_free
0.53% skb_release_data
To reduce the extra CPU load use return values jumping to rx_cleanup
state directly to free them instead of calling skb_queue_tail() and
skb_dequeue() for push/pop respectively.
- 7.87% 0.25% swapper [k] usbnet_bh
- 7.62% usbnet_bh
- 4.81% skb_dequeue
4.74% _raw_spin_unlock_irqrestore
- 1.75% consume_skb
- 0.98% kfree_skbmem
0.78% kmem_cache_free
0.58% skb_release_data
0.53% smsc95xx_rx_fixup
Signed-off-by: Leesoo Ahn <lsahn@xxxxxxxxxx>
---
v2:
- Replace goto label with return statement to reduce goto entropy
- Add CPU load information by perf in commit message
v1 at:
https://patchwork.kernel.org/project/netdevbpf/patch/20221217161851.829497-1-lsahn@xxxxxxxxxx/
---
drivers/net/usb/usbnet.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 64a9a80b2309..6e82fef90dd9 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -555,32 +555,30 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
/*-------------------------------------------------------------------------*/
-static inline void rx_process (struct usbnet *dev, struct sk_buff *skb)
+static inline int rx_process(struct usbnet *dev, struct sk_buff *skb)
{
if (dev->driver_info->rx_fixup &&
!dev->driver_info->rx_fixup (dev, skb)) {
/* With RX_ASSEMBLE, rx_fixup() must update counters */
if (!(dev->driver_info->flags & FLAG_RX_ASSEMBLE))
dev->net->stats.rx_errors++;
- goto done;
+ return 1;
"1" means that you processed 1 byte, not that this is an error, which is
what you want to say here, right?
No not at all..
Please return a negative error value
like I asked this to be changed to last time :(
Could you help me to decide the message type at this point please? I am
confused.
The return value totally depends on how rx_fixup() is. For instance, in
smsc95xx.c, smsc95xx_rx_fixup() function returns 0 in two cases that
1) frame size is greater than ETH_FRAME_LEN(1526 bytes) as follows
1853 /* ETH_FRAME_LEN + 4(CRC) + 2(COE) + 4(Vlan) */
1854 if (unlikely(size > (ETH_FRAME_LEN + 12))) {
1855 netif_dbg(dev, rx_err, dev->net,
1856 "size err header=0x%08x\n", header);
1857 return 0;
1858 }
2) it is failed for skb allocation, but memory?
1870 ax_skb = skb_clone(skb, GFP_ATOMIC);
1871 if (unlikely(!ax_skb)) {
1872 netdev_warn(dev->net, "Error allocating skb\n");
1873 return 0;
1874 }
I guess EPROTO or ENOMEM, one of them could be the value at the point
but I have no ideas..
Best regards,
Leesoo
