On Sun, Jul 26, 2020 at 6:42 AM Willem de Bruijn
<willemdebruijn.ker...@gmail.com> wrote:
>
> On Sat, Jul 25, 2020 at 7:08 PM Han <keepsim...@gmail.com> wrote:
> >
> > My apologies if this is not the right place to ask this question.
> >
> > I'm trying to use UDP GSO to improve the throughput. My testing shows
> > that UDP GSO works with the local server (i.e. loopback interface) but
> > fails with a remote server (in WLAN, via wlan0 interface).
> >
> > My question is: do I need to explicitly enable UDP GSO for wlan0
> > interface? If yes, how do I do it? I searched online but could not
> > find a good answer. I looked at "ethtool" but not clear which option
> > to use:
> >
> > $ ethtool --show-offload wlan0 | grep -i generic-segment
> > generic-segmentation-offload: off [requested on]
>
> Which wireless driver does your device use. Does it have tx checksum offload?
It seems to be "brcmfmac" :
$ readlink /sys/class/net/wlan0/device/driver
../../../../../../../../bus/sdio/drivers/brcmfmac
I think tx checksum offload is off, and I couldn't turn it on. Does
"[fixed]" mean it cannot be changed?
$ ethtool --show-offload wlan0 | grep -i sum
rx-checksumming: off [fixed]
tx-checksumming: off
tx-checksum-ipv4: off [fixed]
tx-checksum-ip-generic: off [fixed]
tx-checksum-ipv6: off [fixed]
tx-checksum-fcoe-crc: off [fixed]
tx-checksum-sctp: off [fixed]
tx-gre-csum-segmentation: off [fixed]
tx-udp_tnl-csum-segmentation: off [fixed]
esp-tx-csum-hw-offload: off [fixed]
Tried this but didn't work:
$ sudo ethtool --offload wlan0 tx on
Cannot change tx-checksumming
Could not change any device features
$ sudo ethtool -K wlan0 tx-checksum-ipv4 on
Could not change any device features
> That is a hard requirement. In udp_send_skb:
>
> if (skb->ip_summed != CHECKSUM_PARTIAL || is_udplite ||
> dst_xfrm(skb_dst(skb))) {
> kfree_skb(skb);
> return -EIO;
> }
>
> > $ ethtool --show-offload wlan0 | grep -i udp-segment
> > tx-udp-segmentation: off [fixed]
>
> This is hardware segmentation offload. It is not required.
