[ovs-dev] [PATCH ovs resend v2] dpctl-netdev: Add the option "pmd" for dump-flows

Ilya Maximets i.maximets at ovn.org
Mon Sep 7 13:01:04 UTC 2020

On 9/7/20 7:29 AM, Tonghao Zhang wrote:
> On Thu, Sep 3, 2020 at 8:51 PM Ilya Maximets <i.maximets at ovn.org> wrote:
>> On 8/24/20 4:44 AM, xiangxia.m.yue at gmail.com wrote:
>>> From: Tonghao Zhang <xiangxia.m.yue at gmail.com>
>>> "ovs-appctl dpctl/dump-flows" added the option
>>> "pmd" which allow user to dump pmd specified.
>>> That option is useful to dump rules of pmd
>>> when we have a large number of rules in dp.
>> Is this a performance concern or just a matter of output readability?
> Yes, performance and the matter of output are considered. Think about
> there is a lots of flows on every
> pmd which may be offloaded.

I understand that it will be faster to not dump flows that wasn't requested,
however, dpctl interface is a debugging interface and should not be used
frequently in normal conditions.  And if you have so many flows that dumping
takes significant amount of time, you might have much more important issues
with inability to change them in time by revalidators.
So, why the performance of this operation is such a concern for you?

>> In case it's only to reduce the size of a printed data, we could just
>> avoid printing flows from PMDs other than requested the same way as
>> other filters work without flow_dump API modifications. This will be
>> much more simple change.
>> What do you think?
>> Best regards, Ilya Maximets.

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