On 10/18/19 12:42 PM, Ferruh Yigit wrote:
On 10/18/2019 8:32 AM, Andrew Rybchenko wrote:
Hi Ferruh,
since I've reviewed I'll reply as I understand it.
On 10/17/19 8:43 PM, Ferruh Yigit wrote:
On 10/17/2019 1:02 PM, pbhagavat...@marvell.com wrote:
From: Pavan Nikhilesh <pbhagavat...@marvell.com>
Add new Rx offload flags `DEV_RX_OFFLOAD_RSS_HASH` and
`DEV_RX_OFFLOAD_FLOW_MARK`. These flags can be used to
enable/disable PMD writes to rte_mbuf fields `hash.rss` and `hash.fdir.hi`
and also `ol_flags:PKT_RX_RSS` and `ol_flags:PKT_RX_FDIR`.
Hi Pavan,
Initially sorry for involving late,
When we expose an interface to the applications, they will expect those will be
respected by underlying PMDs.
As far as I can see drivers are updated to report new added Rx offload flags as
supported capabilities but drivers are not using those flags at all, so
application providing that flag won't really enable/disable anything, I think
this is a problem and it is wrong to lie even for the PMDs J
It is required to let applications know that the offload is supported.
There are a number of cases when an offload cannot be disabled,
but it does not mean that the offload must not be advertised.
Can't disable is something else, although I believe that is rare case, in this
case driver can enable/disable the RSS and representing this as an offload
capability.
It is not enabling/disabling the RSS. It is enabling/disabling RSS hash
delivery
together with an mbuf.
But when user want to configure this offload by setting or unsetting in offload
config, driver just ignores it.
When application enables offload, it says that it needs it and going to use
(required). When the offload is not enabled, application simply don't care.
So, if the information is still provided it does not harm.
If driver see benefits from disabling the offload (e.g. avoid delivery
of RSS hash from NIC to host), it can do it after the patchset.
Yes but I think this patchset shouldn't ignore that disabling the feature is not
implemented yet. If those PMDs that has been updated to report the HASH
capability has RSS enabled by default, I suggest adding a check for this offload
in PMD,
if it is requested to disable (which means not requested for enable), print a
log saying disabling HASH is not supported and set this flag in the offload
configuration to say PMD is configured to calculate the HASH.
Later PMD maintainers may prefer to replace that error log with actual disable
code.
It is possible to do. Of course, it is better to provide real offload
values on get, but
eth_conf is const in rte_eth_dev_configure(), so, we can't change it and
it is good.
So, the only way is rte_eth_rx_queue_info_get().
I guess there is a lot of space for the same improvement for other Rx
offloads
in various PMDs.
Also I worry that it could be not that trivial to do in all effected PMDs.
Specific to `DEV_RX_OFFLOAD_RSS_HASH`, we have already some RSS config
structures and it is part of the 'rte_eth_dev_configure()' API, won't it create
multiple way to do same thing?
No, a new offload is responsible for RSS hash delivery from NIC to host
and fill in in mbuf returned to application on Rx.
What you have described is already happening without the new offload flag and
this is my concern that we are duplicating it.
There is a 'struct rte_eth_rxmode' (under 'struct rte_eth_conf')
which has 'enum rte_eth_rx_mq_mode mq_mode;'
If "mq_mode == ETH_MQ_RX_NONE" hash calculation is disabled, and
'mbuf::hash::rss' is not updated.
No-no. It binds RSS distribution and hash delivery. What the new
offload allows to achieve: I want Rx to spread traffic over many Rx
queues, but I don't need RSS hash.
(Thanks Bruce to helping finding it out)
And for the `ol_flags:PKT_RX_RSS` flag, it was already used to mark that
'mbuf::hash::rss' is valid, right? Is there anything new related that in the
set?
As I understand you mean, ol_flags::PKT_RX_RSS_HASH.
Yes, the new offload allows say if application needs it or now.
Basically it decouples RSS distribution and hash delivery.
Setting 'ol_flags::PKT_RX_RSS_HASH' and 'mbuf::hash::rss' already there and not
changing. I just want to clarify since this is not clear in the commit log.
Only addition is to add a new flag to control PMD to enable/disable hash
calculation (which PMDs ignore in the patch ???)
It is not calculation, but delivery of the value from HW to applications.
Yes, commit log may/should be improved.
Specific to the `DEV_RX_OFFLOAD_FLOW_MARK` and `RTE_FLOW_ACTION_FLAG`, they are
rte_flow actions, application can verify and later request these actions via
rte_flow APIs. Why we are adding an additional RX_OFFLOAD flag for them?
The reason is basically the same as above. HW needs to know in advance,
if application is going to use flow marks and configure Rx queue to enable
the information delivery.
What you described is done via 'rte_flow_create()' API, application will request
those actions via API and Rx queue will be configured accordingly, this is more
dynamic approach. Why application need to set this additional configuration
flag?
More dynamic approach is definitely better, but it is not always possible.
Some PMDs can't even change MTU dynamically or MTU changing requires
restart which is hardly really a dynamic change. Of course, it is
unlikely that
MTU is changed when traffic is running etc, but still possible.
The information about necessity to support flow marks delivery may
be required on Rx queue setup and cannot be changed dynamically when
Rx queue is running and application would like to add flow rule with mark
action.
And as above the new RX offload flags ignored by PMDs, hard to understand what
is the intention here.
Above usage of flags feels like the intention is adding some capability
information for the PMDs more that adding new offload configuration.
If so this is bigger/older problem, and instead of abusing the offload flags we
can think of an API to present device capabilities, and move features.ini
content to the API in long term.
What I really like with these new offload flags for Rx hash and flow mark is
that it makes features which provide information in mbuf on Rx consistent:
- want timestamp? => DEV_RX_OFFLOAD_TIMESTAMP
- want Rx checksum flags => DEV_RX_OFFLOAD_CHECKSUM
- want to strip VLAN? => DEV_RX_OFFLOAD_VLAN_STRIP
- want RSS hash? => DEV_RX_OFFLOAD_RSS_HASH
- want flow mark support? => DEV_RX_OFFLOAD_FLOW_MARK
Also it perfectly fits dynamic mbuf fields and allows to make RSS hash
and flow mark fields dynamic with the new offloads as controls.
Add new packet type set function `rte_eth_dev_set_supported_ptypes`,
allows application to inform PMDs about the packet types it is interested
in. Based on ptypes requested by application PMDs can optimize the Rx path.
OK to the API, but why "Packet type parsing" feature updated to say it should
implement this API?
Is this API really required to say "Packet type parsing" supported by PMD?
As I understand it is not strictly required, but related to the feature.
I am OK with "related", but it is documented as "implements", so doc says it is
required.
Agreed.
For example, if a given PMD doesn't support any packet types that the
application is interested in then the application can disable[1] writes to
`mbuf.packet_type` done by the PMD and use a software ptype parser.
[1] rte_eth_dev_set_supported_ptypes(*port_id*, RTE_PTYPE_UNKNOWN,
NULL, 0);
And for the 7/7 patch, why we are updating all examples, is the API something do
we really need to call for any DPDK application? I am for leaving the default
behavior unless there is a very specific case for set or disable packet typing.
Instead implement a command in testpmd to test this feature.
If an application does not use packet types provided in mbuf, it is
better to inform PMD that the information is not required to allow PMD
to do optimizations.
I can see disabling packet type detection may increase the performance but
sample applications are to demonstrate a specific feature, adding these kind of
APIs will pollute them.
'skeleton' app that shows the most basic code for forwarding sample, why it is
now having "experimental" 'set_supported_ptypes()' API? Same for other. As said
before I think a testpmd command suits better here.
May be you're right and we should reconsider which applications
are updated and which are ignored. I guess before the criteria
was simple: don't use packet type information, say so to take
benefits from all possible optimizations.
Yes, may be it would be better to have it as the
default behaviour, but it would be behaviour change in comparison
to previous DPDK releases and it is better to avoid it.
Sorry I missed why not calling this function cause behavior change? I think it
is other way around, no?
Just misunderstanding. What I was trying to say is that it could
be more logical to have packet type parsing and delivery
disabled by default (as we have for all other offloads), but
it would be behaviour change from application point of view.
That's why it is necessary to disable explicitly.
Thanks,
Andrew.
Thanks,
Andrew.
v12 Changes:
-----------
- Rebase onto next-net.
v11 Changes:
-----------
- Use RTE_DIM to get array size.
- Since we are using a list of MASKs to validate ptype_mask return -EINVAL
if any unknown mask is set.
- Rebase to TOT.
v10 Changes:
-----------
- Modify ptype_mask validation in set_supported_ptypes.(Andrew)
v9 Changes:
----------
- Add ptype_mask validation in set_supported_ptypes.(Andrew)
- Make description more verbose.
v8 Changes:
----------
- Make description more verbose.
- Set RTE_PTYPE_UNKNOWN in set_ptypes array when either get ot set ptypes
is not supported by ethernet device.
v7 Changes:
----------
- Fix unused variable in net/octeontx2
v6 Changes:
----------
- Add additional checks for set supported ptypes.(Andrew)
- Clarify `rte_eth_dev_set_supported_ptypes` documentation.
- Remove DEV_RX_OFFLOAD_FLOW_MARK emulation from net/octeontx2.
v5 Changes:
----------
- Fix typos.
v4 Changes:
----------
- Set the last element in set_ptype array as RTE_PTYPE_UNKNOWN to mark the end
of array.
- Fix invalid set ptype function call in examples.
- Remove setting rte_eth_dev_set_supported_ptypes to UNKNOWN in l3fwd-power.
v3 Changes:
----------
- Add missing release notes. (Andrew)
- Re-word various descriptions.
- Fix ptype set logic.
v2 Changes:
----------
- Update release notes. (Andrew)
- Redo commit logs. (Andrew)
- Disable ptype parsing for unsupported examples. (Jerin)
- Disable RSS write only in generic mode eventdev_pipeline. (Jerin)
- Modify set_supported_ptypes function to return successfuly set mask
instead of failure.
- Dropped set_supported_ptypes to drivers by handling in library
layer, interested PMD can add it in.
Pavan Nikhilesh (7):
ethdev: add set ptype function
ethdev: add mbuf RSS update as an offload
ethdev: add flow action type update as an offload
drivers/net: update Rx RSS hash offload capabilities
drivers/net: update Rx flow flag and mark capabilities
examples/eventdev_pipeline: add new Rx RSS hash offload
examples: disable Rx packet type parsing
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