Hi From: Ananyev, Konstantin > Hi Matan, > > > > > > > > > > >>>> On 11/7/2019 12:35 PM, Dekel Peled wrote: > > > > > > > > > >>>>> @@ -1266,6 +1286,18 @@ struct rte_eth_dev * > > > > > > > > > >>>>> > > > > > > > > > >>>> RTE_ETHER_MAX_LEN; > > > > > > > > > >>>>> } > > > > > > > > > >>>>> > > > > > > > > > >>>>> + /* > > > > > > > > > >>>>> + * If LRO is enabled, check that the maximum > > > > > aggregated > > > > > > > > > packet > > > > > > > > > >>>>> + * size is supported by the configured device. > > > > > > > > > >>>>> + */ > > > > > > > > > >>>>> + if (dev_conf->rxmode.offloads & > > > > > > > > > DEV_RX_OFFLOAD_TCP_LRO) { > > > > > > > > > >>>>> + ret = check_lro_pkt_size( > > > > > > > > > >>>>> + port_id, dev_conf- > > > > > > > > > >>>>> rxmode.max_lro_pkt_size, > > > > > > > > > >>>>> + > > > > > > > > > >>>>> dev_info.max_lro_pkt_size); > > > > > > > > > >>>>> + if (ret != 0) > > > > > > > > > >>>>> + goto rollback; > > > > > > > > > >>>>> + } > > > > > > > > > >>>>> + > > > > > > > > > >>>> > > > > > > > > > >>>> This check forces applications that enable LRO to > > > > > > > > > >>>> provide > > > > > > > > > >> 'max_lro_pkt_size' > > > > > > > > > >>>> config value. > > > > > > > > > >>> > > > > > > > > > >>> Yes.(we can break an API, we noticed it) > > > > > > > > > >> > > > > > > > > > >> I am not talking about API/ABI breakage, that part is OK. > > > > > > > > > >> With this check, if the application requested LRO > > > > > > > > > >> offload but not provided 'max_lro_pkt_size' value, > > > > > > > > > >> device configuration will > > > > > fail. > > > > > > > > > >> > > > > > > > > > > Yes > > > > > > > > > >> Can there be a case application is good with whatever > > > > > > > > > >> the PMD can support as max? > > > > > > > > > > Yes can be - you know, we can do everything we want > > > > > > > > > > but it is better to be > > > > > > > > > consistent: > > > > > > > > > > Due to the fact of Max rx pkt len field is mandatory > > > > > > > > > > for JUMBO offload, max > > > > > > > > > lro pkt len should be mandatory for LRO offload. > > > > > > > > > > > > > > > > > > > > So your question is actually why both, non-lro packets > > > > > > > > > > and LRO packets max > > > > > > > > > size are mandatory... > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think it should be important values for net > > > > > > > > > > applications > > > > > management. > > > > > > > > > > Also good for mbuf size managements. > > > > > > > > > > > > > > > > > > > >>> > > > > > > > > > >>>> - Why it is mandatory now, how it was working > > > > > > > > > >>>> before if it is mandatory value? > > > > > > > > > >>> > > > > > > > > > >>> It is the same as max_rx_pkt_len which is mandatory > > > > > > > > > >>> for jumbo frame > > > > > > > > > >> offload. > > > > > > > > > >>> So now, when the user configures a LRO offload he > > > > > > > > > >>> must to set max lro pkt > > > > > > > > > >> len. > > > > > > > > > >>> We don't want to confuse the user here with the max > > > > > > > > > >>> rx pkt len > > > > > > > > > >> configurations and behaviors, they should be with same > logic. > > > > > > > > > >>> > > > > > > > > > >>> This parameter defines well the LRO behavior. > > > > > > > > > >>> Before this, each PMD took its own interpretation to > > > > > > > > > >>> what should be the > > > > > > > > > >> maximum size for LRO aggregated packets. > > > > > > > > > >>> Now, the user must say what is his intension, and > > > > > > > > > >>> the ethdev can limit it > > > > > > > > > >> according to the device capability. > > > > > > > > > >>> By this way, also, the PMD can organize\optimize its > > > > > > > > > >>> data-path > > > > > more. > > > > > > > > > >>> Also, the application can create different mempools > > > > > > > > > >>> for LRO queues to > > > > > > > > > >> allow bigger packet receiving for LRO traffic. > > > > > > > > > >>> > > > > > > > > > >>>> - What happens if PMD doesn't provide > > > > > > > > > >>>> 'max_lro_pkt_size', so it is > > > > > > > '0'? > > > > > > > > > >>> Yes, you can see the feature description Dekel added. > > > > > > > > > >>> This patch also updates all the PMDs support an LRO > > > > > > > > > >>> for > > > > > > > > > >>> non-0 > > > > > value. > > > > > > > > > >> > > > > > > > > > >> Of course I can see the updates Matan, my point is > > > > > > > > > >> "What happens if PMD doesn't provide > > > > > > > > > >> 'max_lro_pkt_size'", > > > > > > > > > >> 1) There is no check for it right, so it is acceptable? > > > > > > > > > > > > > > > > > > > > There is check. > > > > > > > > > > If the capability is 0, any non-zero configuration will > > > > > > > > > > fail. > > > > > > > > > > > > > > > > > > > >> 2) Are we making this filed mandatory to provide for > > > > > > > > > >> PMDs, it is easy to make new fields mandatory for > > > > > > > > > >> PMDs but is this really > > > > > > > necessary? > > > > > > > > > > > > > > > > > > > > Yes, for consistence. > > > > > > > > > > > > > > > > > > > >>> > > > > > > > > > >>> as same as max rx pkt len, no? > > > > > > > > > >>> > > > > > > > > > >>>> - What do you think setting 'max_lro_pkt_size' > > > > > > > > > >>>> config value to what PMD provided if application > > > > > > > > > >>>> doesn't provide > > > it? > > > > > > > > > >>> Same answers as above. > > > > > > > > > >>> > > > > > > > > > >> > > > > > > > > > >> If application doesn't care the value, as it has been > > > > > > > > > >> till now, and not provided explicit > > > > > > > > > >> 'max_lro_pkt_size', why not ethdev level use the > > > > > > > > > >> value provided by PMD instead > > > of failing? > > > > > > > > > > > > > > > > > > > > Again, same question we can ask on max rx pkt len. > > > > > > > > > > > > > > > > > > > > Looks like the packet size is very important value > > > > > > > > > > which should be set by > > > > > > > > > the application. > > > > > > > > > > > > > > > > > > > > Previous applications have no option to configure it, > > > > > > > > > > so they haven't > > > > > > > > > configure it, (probably cover it somehow) I think it is > > > > > > > > > our miss to supply this info. > > > > > > > > > > > > > > > > > > > > Let's do it in same way as we do max rx pkt len (as > > > > > > > > > > this patch main > > > > > idea). > > > > > > > > > > Later, we can change both to other meaning. > > > > > > > > > > > > > > > > > > > > > > > > > > > > I think it is not a good reason to introduce a new > > > > > > > > > mandatory config option for application because of > 'max_rx_pkt_len' does it. > > > > > > > > > > > > > > > > It is mandatory only if LRO offload is configured. > > > > > > > > > > > > > > So max_rx_pkt_len will remain max size of one packet, while > > > > > > > max_lro_len will be max accumulate size for each LRO session? > > > > > > > > > > > > > > > > > > > Yes. > > > > > > > > > > > > > BTW, I think that for ixgbe max lro is RTE_IPV4_MAX_PKT_LEN. > > > > > > > > > > > > Please see my change in drivers/net/ixgbe/ixgbe_ethdev.c. > > > > > > Change to RTE_IPV4_MAX_PKT_LEN? > > > > > > > > > > > > > ixgbe_vf, as I remember, doesn’t support LRO at all. > > > > > > > > > > > > Please see my change in > > > > > > drivers/net/ixgbe/ixgbe_vf_representor.c > > > > > > Remove it? > > > > > > > > > > Yes, please for both. > > > > > > > > Will change in v5. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Will it work, if: > > > > > > > > > - If application doesn't provide this value, use the PMD > > > > > > > > > max > > > > > > > > > > > > > > > > May cause a problem if the mbuf size is not enough for the > > > > > > > > PMD > > > > > maximum. > > > > > > > > > > > > > > Another question, what will happen if PMD will ignore that > > > > > > > value and will generate packets bigger then requested? > > > > > > > > > > > > PMD should use this value and not ignore it. > > > > > > > > > > Hmm, ok but this patch updates mxl driver only... > > > > > I suppose you expect other PMD maintainers to do the job for > > > > > their PMDs, right? > > > > > If so, are they aware (and agree) for this new hard requirement > > > > > and changes required? > > > > > Again what PMD should do if it can't support exact value? > > > > > Let say user asked max_lro_size=20KB but PMD can do only 16KB or > > > 24KB? > > > > > Should it fail, or round to smallest, or ...? > > > > > > > > > > Actually I wonder, should it really be a hard requirement or > > > > > more like a guidance to PMD? > > > > > Why app needs and *exact* value for LRO size? > > > > > > > > The exact value should be configured to HW as LRO session limit. > > > > > > But if the HW can't support this exact value, see the example above? > > > In fact, shouldn't we allow PMD to forbid user to configure max LRO size? > > > Let say if in dev_info max_lro_size==0, then PMD doesn't support LRO > > > size configuration at all. > > > That way PMDs who do support LRO, but don't want to (can't to) > > > support configurable LRO size will stay untouched. > > > > Each HW should support packet size limitation no matter if it is LRO packet > or not: > > How does the PMD limit the packet size for max rx packet len conf? > > How does the PMD limit the packet size for the mbuf size? > > Not sure I understand your statement and questions above... > For sure PMD has to support max_rx_pktlen., but how does it relate to > max_lro?
You said that HW may not support LRO max size configuration. I answered that as same as the HW can limit packets to the configuration of max_rx_pkt_len, so it can limit LRO packets size here too. For simplifications: Rx Queues which are not configured to do LRO offload should limit their packets to the max_rx_pkt_len field. Rx Queues which are configured to do LRO offload should limit their packets to the max_lro_pkt_len new field. In addition, both should limit the packets size to the mbuf size of the Rx mempool configured to the Rx queue( if scatter offload is not enabled).