From: Vlad Buslov <vladbu@nvidia•com>
To: Simon Horman <simon.horman@corigine•com>
Cc: Jamal Hadi Salim <jhs@mojatatu•com>,
David Miller <davem@davemloft•net>,
Jakub Kicinski <kuba@kernel•org>,
Cong Wang <xiyou.wangcong@gmail•com>,
"Jiri Pirko" <jiri@mellanox•com>, <netdev@vger•kernel.org>,
<oss-drivers@corigine•com>,
Baowen Zheng <baowen.zheng@corigine•com>,
"Louis Peens" <louis.peens@corigine•com>
Subject: Re: [PATCH net-next 1/3] flow_offload: allow user to offload tc action to net device
Date: Tue, 27 Jul 2021 17:38:51 +0300 [thread overview]
Message-ID: <ygnh7dhbrfd0.fsf@nvidia.com> (raw)
In-Reply-To: <20210727130419.GA6665@corigine.com>
On Tue 27 Jul 2021 at 16:04, Simon Horman <simon.horman@corigine•com> wrote:
> On Thu, Jul 22, 2021 at 09:33:09AM -0400, Jamal Hadi Salim wrote:
>> On 2021-07-22 9:29 a.m., Vlad Buslov wrote:
>> > On Thu 22 Jul 2021 at 12:19, Simon Horman <simon.horman@corigine•com> wrote:
>> > > From: Baowen Zheng <baowen.zheng@corigine•com>
>> > >
>> > > Use flow_indr_dev_register/flow_indr_dev_setup_offload to
>> > > offload tc action.
>> > >
>> > > We offload the tc action mainly for ovs meter configuration.
>> > > Make some basic changes for different vendors to return EOPNOTSUPP.
>> > >
>> > > We need to call tc_cleanup_flow_action to clean up tc action entry since
>> > > in tc_setup_action, some actions may hold dev refcnt, especially the mirror
>> > > action.
>> > >
>> > > As per review from the RFC, the kernel test robot will fail to run, so
>> > > we add CONFIG_NET_CLS_ACT control for the action offload.
>> > >
>> > > Signed-off-by: Baowen Zheng <baowen.zheng@corigine•com>
>> > > Signed-off-by: Louis Peens <louis.peens@corigine•com>
>> > > Signed-off-by: Simon Horman <simon.horman@corigine•com>
>> > > ---
>> > > drivers/net/ethernet/broadcom/bnxt/bnxt_tc.c | 2 +-
>> > > .../ethernet/mellanox/mlx5/core/en/rep/tc.c | 3 ++
>>
>> > > void *data,
>> > > void (*cleanup)(struct flow_block_cb *block_cb))
>> > > {
>> > > + if (!netdev)
>> > > + return -EOPNOTSUPP;
>> > > +
>> > > switch (type) {
>> > > case TC_SETUP_BLOCK:
>> > > return mlx5e_rep_indr_setup_block(netdev, sch, cb_priv, type_data,
>> > > diff --git a/drivers/net/ethernet/netronome/nfp/flower/offload.c b/drivers/net/ethernet/netronome/nfp/flower/offload.c
>>
>> [..]
>>
>> > > + /* offload actions to hardware if possible */
>> > > + tcf_action_offload_cmd(actions, extack);
>> > > +
>> >
>> > I think this has already been suggested for RFC, but some sort of
>> > visibility for offload status of action would be extremely welcome.
>> > Perhaps "IN_HW" flag and counter, similar to what we have for offloaded
>> > filters.
>> >
>>
>> Also showing a tc command line in the cover letter on how one would
>> ask for a specific action to be offloaded.
>
> In practice actions are offloaded when a flow using them is offloaded.
> So I think we need to consider what the meaning of IN_HW is.
>
> Is it that:
>
> * The driver (and potentially hardware, though not in our current
> implementation) has accepted the action for offload;
> * That a classifier that uses the action has bee offloaded;
> * Or something else?
I think we have the same issue with filters - they might not be in
hardware after driver callback returned "success" (due to neigh state
being invalid for tunnel_key encap, for example).
>
> With regards to a counter, I'm not quite sure what this would be:
>
> * The number of devices where the action has been offloaded (which ties
> into the question of what we mean by IN_HW)
> * The number of offloaded classifier instances using the action
> * Something else
I would prefer to have semantics similar to filters:
1. Count number of driver callbacks that returned "success".
2. If count > 0, then set in_hw flag.
3. Set in_hw_count to success count.
This would allow user to immediately determine whether action passed
driver validation.
>
> Regarding a flag to control offload:
>
> * For classifiers (at least the flower classifier) there is the skip_sw and
> skip_hw flags, which allow control of placement of a classifier in SW and
> HW.
> * We could add similar flags for actions, which at least in my
> world view would have the net-effect of controlling which classifiers can
> be added to sw and hw - f.e. a classifier that uses an action marked
> skip_hw could not be added to HW.
> * Doing so would add some extra complexity and its not immediately apparent
> to me what the use-case would be given that there are already flags for
> classifiers.
Yeah, adding such flag for action offload seems to complicate things.
Also, "skip_sw" flag doesn't even make much sense for actions. I thought
that "skip_hw" flag would be nice to have for users that would like to
avoid "spamming" their NIC drivers (potentially causing higher latency
and resource consumption) for filters/actions they have no intention to
offload to hardware, but I'm not sure how useful is that option really
is.
next prev parent reply other threads:[~2021-07-27 14:39 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-22 9:19 [PATCH net-next 0/3] flow_offload: hardware offload of TC actions Simon Horman
2021-07-22 9:19 ` [PATCH net-next 1/3] flow_offload: allow user to offload tc action to net device Simon Horman
2021-07-22 12:24 ` Roi Dayan
2021-07-22 13:19 ` Simon Horman
2021-07-22 13:29 ` Vlad Buslov
2021-07-22 13:33 ` Jamal Hadi Salim
2021-07-27 13:04 ` Simon Horman
2021-07-27 14:38 ` Vlad Buslov [this message]
2021-07-27 16:13 ` Jamal Hadi Salim
2021-07-27 16:47 ` Vlad Buslov
2021-07-28 7:46 ` Simon Horman
2021-07-28 8:05 ` Vlad Buslov
2021-07-28 13:51 ` Jamal Hadi Salim
2021-07-28 14:46 ` Simon Horman
2021-07-30 10:17 ` Jamal Hadi Salim
2021-07-30 11:40 ` Vlad Buslov
2021-08-03 9:57 ` Jamal Hadi Salim
2021-08-03 12:02 ` tc offload debug-ability Jamal Hadi Salim
2021-08-03 12:14 ` Vlad Buslov
2021-08-03 12:50 ` Jamal Hadi Salim
2021-08-03 13:34 ` Ido Schimmel
2021-07-30 13:20 ` [PATCH net-next 1/3] flow_offload: allow user to offload tc action to net device Simon Horman
2021-08-03 10:14 ` Jamal Hadi Salim
2021-08-03 11:36 ` Simon Horman
2021-08-03 11:45 ` Jamal Hadi Salim
2021-08-03 12:31 ` Simon Horman
2021-08-03 13:01 ` Jamal Hadi Salim
2021-08-03 14:46 ` Simon Horman
2021-07-22 13:57 ` kernel test robot
2021-07-22 15:31 ` kernel test robot
2021-08-03 10:50 ` Jamal Hadi Salim
2021-08-03 11:05 ` Jamal Hadi Salim
2021-08-03 11:31 ` Simon Horman
2021-07-22 9:19 ` [PATCH net-next 2/3] flow_offload: add process to delete offloaded actions from " Simon Horman
2021-07-22 14:25 ` Vlad Buslov
2021-07-22 14:50 ` kernel test robot
2021-07-22 17:07 ` kernel test robot
2021-08-03 10:59 ` Jamal Hadi Salim
2021-07-22 9:19 ` [PATCH net-next 3/3] flow_offload: add process to update action stats from hardware Simon Horman
2021-07-22 14:55 ` Vlad Buslov
2021-08-03 11:24 ` Jamal Hadi Salim
2021-08-03 11:35 ` Simon Horman
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