Interface proposal for rx classification using ethtool
Subsystems (2)
Here is the proposed design for implementing an interface to add, delete and manage rules for RX packet classification on ethertool with niu as the first target hardware. This is the second installment of network flow classification support (the first one was for rx flow distribution based on hashing that was added in June). Please review and send your feedback.
1. The ethertool application will have an interface to add a classification rule and the target RX ring for packets that match the rule. The rules are added on a per port basis. Each new rule that is added is represented by a unique ID. This ID can be used by the user to delete the rule or query the details of the rule (both interfaces provided via ethertool).
2. Here is the list of cmds/interfaces that will be added to ethertool (as suboptions in the rx_classification option) to achieve this:
- get the number of RX rings available to this port.
- add a rule (flow-tuple/mask to RX ring mapping)
- delete a rule
- query a particular rule or all rules for this port
3. Within ethertool, there will be a manager for these rules that will order the rules on a per port basis according to the policy chosen by the user. In the first cut, the policy will be hardcoded as longest prefix first ordering. Before adding any rules to the hardware, the rule manager will first query the hardware for the ordering that it implements for matching, e.g., low-to-high (as in case of niu TCAM). This information will be taken into account while writing to the rule-manager and to the hardware.
4. In the niu driver, there will be a local array of the tcam_entries (for supporting queries from ethertool).
5. There is no protection against inconsistencies between the tcam entries and the user view of it that can arise if multiple instances of ethertool happen to write the same rule (tcam_entry).
thanks,
--santwona
David Miller
maintainerFrom: [email protected]
Date: Mon, 29 Sep 2008 10:28:07 -0700
Quoted 5 lines
Here is the proposed design for implementing an interface to add, delete and manage rules for RX packet classification on ethertool with niu as the first target hardware. This is the second installment of network flow classification support (the first one was for rx flow distribution based on hashing that was added in June). Please review and send your feedback.
This looks mostly fine to me, thanks for working on this.
I do have one question though.
At least to some extent the user will have to have a way to figure out that multiple interfaces correspond to one instance of the TCAM. Because this determines sharing and other aspects, right?
How it seems to work in your description is that the user operates on (for example) eth0 and eth1 as if they were independant objects, but if the TCAM fills up that will be seen equally by operations on both interfaces.
But, to be honest this is a minor detail.
They may also be value in allowing TCAM entries to be locked by the kernel and thus be unmodifyable by the user.
For example, in NIU, those special workaround entries we add to handle IP fragments would be a candidate for this.
Quoted 9 lines · David Miller
From: [email protected]
Date: Mon, 29 Sep 2008 10:28:07 -0700Quoted 5 lines
Here is the proposed design for implementing an interface to add, delete and manage rules for RX packet classification on ethertool with niu as the first target hardware. This is the second installment of network flow classification support (the first one was for rx flow distribution based on hashing that was added in June). Please review and send your feedback.
Quoted 8 lines
This looks mostly fine to me, thanks for working on this.
I do have one question though.
At least to some extent the user will have to have a way to figure out that multiple interfaces correspond to one instance of the TCAM. Because this determines sharing and other aspects, right?
That will not be the case as the driver will partition the TCAM on a per interface basis. So the entries for each interface will be independent of each other. This has been done to make the ethtool interface independent of the TCAM implementation, i.e., if there are multiple TCAMs in any future revs of the hardware or in any other hardware, the per port API should work.
Quoted 5 lines
How it seems to work in your description is that the user operates on (for example) eth0 and eth1 as if they were independant objects, but if the TCAM fills up that will be seen equally by operations on both interfaces.
Each partition in the TCAM will fill up independently for each interface.
Quoted 5 lines
But, to be honest this is a minor detail.
They may also be value in allowing TCAM entries to be locked by the kernel and thus be unmodifyable by the user.
That will be the case. All updates will be done by the driver to implement the partitioning.
Quoted 3 lines
For example, in NIU, those special workaround entries we add to handle IP fragments would be a candidate for this.
That is right. In fact these entries will be put in by the driver and will not be exported to the user. The partitioning for each port will start in the region after these entries.
--santwona
Quoted 28 lines · On Sep 29, 2008, at 12:28 PM, [email protected] wrote:
Here is the proposed design for implementing an interface to add, delete and manage rules for RX packet classification on ethertool with niu as the first target hardware. This is the second installment of network flow classification support (the first one was for rx flow distribution based on hashing that was added in June). Please review and send your feedback.
1. The ethertool application will have an interface to add a classification rule and the target RX ring for packets that match the rule. The rules are added on a per port basis. Each new rule that is added is represented by a unique ID. This ID can be used by the user to delete the rule or query the details of the rule (both interfaces provided via ethertool).
2. Here is the list of cmds/interfaces that will be added to ethertool (as suboptions in the
rx_classificationoption) to achieve this:- get the number of RX rings available to this port.
- add a rule (flow-tuple/mask to RX ring mapping)
- delete a rule
- query a particular rule or all rules for this port3. Within ethertool, there will be a manager for these rules that will order the rules on a per port basis according to the policy chosen by the user. In the first cut, the policy will be hardcoded as longest prefix first ordering. Before adding any rules to the hardware, the rule manager will first query the hardware for the ordering that it implements for matching, e.g., low-to-high (as in case of niu TCAM). This information will be taken into account while writing to the rule-manager and to the hardware.
Quoted 6 lines
4. In the niu driver, there will be a local array of the
tcam_entries(for supporting queries from ethertool).5. There is no protection against inconsistencies between the tcam entries and the user view of it that can arise if multiple instances of ethertool happen to write the same rule (
tcam_entry).
What's the state of patches for this work?
- k
Quoted 5 lines
What's the state of patches for this work?
- k
I am working on it. The goal is to submit the patches by middle of November.
--santwona
Quoted 4 lines
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