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? Please return a negative error value like I asked this to be changed to last time :( thanks, greg k-h
