Hi everyone, I agree with opinion #3 as well. It allows us to keep 0 as “unknown" (i.e., not set by the driver), and we can specify ~0 as “Not Applicable” (typically the case for virtual links) and change format_vnet_hw_interface_link_speed accordingly.
Best regards, Mohammed > On 18 Jan 2021, at 12:06, Benoit Ganne (bganne) via lists.fd.io > <bganne=cisco....@lists.fd.io> wrote: > > Hi Matt, > > I am adding the list so that maybe VPP DPDK plugin users/maintainers can > chime in. > In my opinion #3 setting link speed to ~0 makes sense as VPP usually use ~0 > as "invalid". > > The original issue I attempted to fix in DPDK was that the Mellanox DPDK > driver was not able to return link status in Azure because it refused to > return link status if it could not determine link speed. My original proposed > change in DPDK was just for the Mellanox DPDK driver to return link status > anyway but not link speed in that case (as eg. Intel drivers do). It ended up > being a bit more complicated in the end 😊 > > Best > ben > >> -----Original Message----- >> From: Matthew Smith <mgsm...@netgate.com> >> Sent: vendredi 15 janvier 2021 21:12 >> To: Benoit Ganne (bganne) <bga...@cisco.com> >> Cc: Jim Thompson <j...@netgate.com> >> Subject: DPDK change in link speed convention >> >> >> Hi Benoit, >> >> i saw a change to DPDK which listed "Suggested-by: Benoit Ganne >> <bga...@cisco.com <mailto:bga...@cisco.com> >" - >> - >> https://github.com/DPDK/dpdk/commit/810b17d116f03783843d23ac900a3794675f66 >> 16#diff-2e1c01c3a61689ba8e51c0cf41d4d8153870532b8d64ea0847dff7a169e54bef. >> >> Due to this change, it seems that rte_eth_link_get_nowait() can now return >> ~0 for ports where the link speed is unknown or for virtual links. Along >> with another change >> (https://github.com/DPDK/dpdk/commit/b415b7a06856b148ace29ffcc6e9740a12b9e >> c33#diff-c943f71001a82a273432fb087f7cd461d9666ee5cfd58a0b1b2b93b68d9f6234) >> this has resulted in VPP reporting the link speed of DPDK virtio >> interfaces as 4294966296 kbps. This is because the VPP DPDK plugin calls >> vnet_hw_interface_set_link_speed() with the link speed value retrieved by >> rte_eth_link_get_nowait() multiplied by 1000 to convert Mbps to kbps. When >> rte_eth_link_get_nowait() returns a link speed of ~0, multiplying it by >> 1000 overflows a u32 and the value that is set on the vnet_hw_interface_t >> is 4294966296. >> >> It seems like something different should happen in the VPP DPDK plugin >> when the link speed is reported by DPDK as ~0. Maybe one of these options >> would be good: >> >> 1. Don't call vnet_hw_interface_set_link_speed() at all in this case. If >> the current link speed is being reported as "unknown", maybe whatever >> value is set on the VPP hw interface should be left as it is. >> 2. Call vnet_hw_interface_set_link_speed() with a link speed of 0. The >> default link speed value of a new vnet_hw_interface_t is 0, so 0 could be >> viewed as the de facto VPP version of "unknown". >> 3. Call vnet_hw_interface_set_link_speed() with a link speed of ~0 rather >> than (~0 * 1000) as is currently done. And agree/document that this value >> means "unknown" in VPP. >> >> Since the DPDK commit that announced this change had a Suggested-by header >> that mentioned you, I wanted to find out if you had thoughts on how this >> should be handled or if you already had some work in progress to deal with >> this. >> >> Thanks! >> -Matt > > > >
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