lkml.org 
[lkml]   [2022]   [Dec]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2] usbnet: optimize usbnet_bh() to reduce CPU load
From

On 22. 12. 21. 16:30, Greg KH wrote:
> On Wed, Dec 21, 2022 at 04:19:45PM +0900, Leesoo Ahn wrote:
>> 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@ooseel.net>
>>>> ---
>>>> 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(-)
>>>>
>>>> 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.
> I do not know, pick something that seems correct and we can go from
> there. The important thing is that it is a -ERR value, not a positive
> one as that makes no sense for kernel functions.

Thank you for reviewing, v3 will be sent soon.

Best regards,
Leesoo

\
 
 \ /
  Last update: 2023-03-26 23:16    [W:0.060 / U:1.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site