[ovs-dev] [PATCH 1/2] datapath: Mega flow implementation

Jesse Gross jesse at nicira.com
Wed Jun 19 23:09:57 UTC 2013

What is the reason need for iterating through the mask list itself
when destroying the table instead of doing it as the flows are
deleted? Doing it that way would both avoid the need to have multiple
list deletion functions and the differences between the RCU and
non-RCU versions of ovs_flow_free().

One issue that comes to mind is the RCU barrier when the module is
unloaded but there are other ways to fix that.

On Wed, Jun 19, 2013 at 2:09 PM, Andy Zhou <azhou at nicira.com> wrote:
> Jesse,
> The following patch is an incremental patch on top of yours.
>  -- Fix a few small bugs introduced by the cleanup patch.
>  -- Make mask list per table.
> I believe this implementation will address the rcu lock issues we discussed
> off line.
> Would you please review?
> Thanks,
> --andy
> On Tue, Jun 18, 2013 at 4:35 PM, Jesse Gross <jesse at nicira.com> wrote:
>> On Tue, Jun 18, 2013 at 4:15 PM, Andy Zhou <azhou at nicira.com> wrote:
>> > Add wildcarded flow support in kernel datapath.
>> >
>> > Wildcarded flow can improve OVS flow set up performance by avoid sending
>> > matching new flows to the user space program. The exact performance
>> > boost
>> > will largely dependent on wildcarded flow hit rate.
>> >
>> > In case all new flows hits wildcard flows, the flow set up rate is
>> > within 5% of that of linux bridge module.
>> >
>> > Pravin has made significant contributions to this patch. Including API
>> > clean ups and bug fixes.
>> >
>> > Co-authored-by: Pravin B Shelar <pshelar at nicira.com>
>> > Signed-off-by: Pravin B Shelar <pshelar at nicira.com>
>> > Signed-off-by: Andy Zhou <azhou at nicira.com>
>> I made some incremental changes, can you take a look to see if they
>> seem reasonable to you?
>> Here are the main blocks:
>>  - Additional interface documentation.
>>  - Fix memory leak when installing a new flow if there is an
>> allocation failure for the mask.
>>  - Require Ethernet addresses to be present in the key, as before.
>>  - Make SNAP handling a little more integrated with the rest of the
>> parsing and validation code.
>>  - Make ovs_flow_free() and ovs_deferred_flow_free() have exactly the
>> same behavior, just with the addition of RCU, to avoid possible
>> confusion.
>>  - Return errors directly rather than through an intermediate variable
>> in ovs_flow_extract() and children.
>>  - Enforce an exact match for the outer EtherType for vlan packets,
>> similar to what we do for other protocols.
>>  - Miscellaneous style fixes.

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