| Message ID | 20221221075924.1141346-1-lsahn@ooseel.net (mailing list archive) |
|---|---|
| State | Deferred |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v3] usbnet: optimize usbnet_bh() to reduce CPU load | expand |
On Wed, 2022-12-21 at 16:59 +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@ooseel.net> > --- > v3: > - Replace return values with proper -ERR values in rx_process() > > 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@ooseel.net/ This looks like net-next material. We have already submitted the networking pull request to Linus for v6.2 and therefore net-next is closed for new drivers, features, code refactoring and optimizations. We are currently accepting bug fixes only. Please repost when net-next reopens after Jan 2nd, including the expected 'net-next' tag into the subject line. RFC patches sent for review only are obviously welcome at any time. [...] > @@ -1528,13 +1526,14 @@ static void usbnet_bh (struct timer_list *t) > entry = (struct skb_data *) skb->cb; > switch (entry->state) { > case rx_done: > - entry->state = rx_cleanup; > - rx_process (dev, skb); > + if (rx_process(dev, skb)) > + goto cleanup; You can avoid this additional label (which is a little confusing inside a switch) factoring out a usb_free_skb(skb) helper and calling it here and under the rx_cleanup case. Cheers, Paolo
22. 12. 22. 20:13에 Paolo Abeni 이(가) 쓴 글: > On Wed, 2022-12-21 at 16:59 +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@ooseel.net> >> --- >> v3: >> - Replace return values with proper -ERR values in rx_process() >> >> 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@ooseel.net/ > > This looks like net-next material. > > We have already submitted the networking pull request to Linus > for v6.2 and therefore net-next is closed for new drivers, features, > code refactoring and optimizations. We are currently accepting > bug fixes only. > > Please repost when net-next reopens after Jan 2nd, including the > expected 'net-next' tag into the subject line > > RFC patches sent for review only are obviously welcome at any time. > > [...] > >> @@ -1528,13 +1526,14 @@ static void usbnet_bh (struct timer_list *t) >> entry = (struct skb_data *) skb->cb; >> switch (entry->state) { >> case rx_done: >> - entry->state = rx_cleanup; >> - rx_process (dev, skb); >> + if (rx_process(dev, skb)) >> + goto cleanup; > > You can avoid this additional label (which is a little confusing inside > a switch) factoring out a usb_free_skb(skb) helper and calling it here > and under the rx_cleanup case. Thank you for the information and feedback, it will be in v4 when net-next reopens. Best regards, Leesoo
diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index 64a9a80b2309..98d594210df4 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 -EPROTO; } // else network stack removes extra byte if we forced a short packet /* all data was already cloned from skb inside the driver */ if (dev->driver_info->flags & FLAG_MULTI_PACKET) - goto done; + return -EALREADY; if (skb->len < ETH_HLEN) { dev->net->stats.rx_errors++; dev->net->stats.rx_length_errors++; netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len); - } else { - usbnet_skb_return(dev, skb); - return; + return -EPROTO; } -done: - skb_queue_tail(&dev->done, skb); + usbnet_skb_return(dev, skb); + return 0; } /*-------------------------------------------------------------------------*/ @@ -1528,13 +1526,14 @@ static void usbnet_bh (struct timer_list *t) entry = (struct skb_data *) skb->cb; switch (entry->state) { case rx_done: - entry->state = rx_cleanup; - rx_process (dev, skb); + if (rx_process(dev, skb)) + goto cleanup; continue; case tx_done: kfree(entry->urb->sg); fallthrough; case rx_cleanup: +cleanup: usb_free_urb (entry->urb); dev_kfree_skb (skb); continue;
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@ooseel.net> --- v3: - Replace return values with proper -ERR values in rx_process() 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@ooseel.net/ --- drivers/net/usb/usbnet.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-)