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Subject: Re: [PATCH net-next 03/21] ethtool, stats: introduce standard XDP
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To:     Saeed Mahameed <saeed@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>,
        Tariq Toukan <ttoukan.linux@gmail.com>,
        Tariq Toukan <tariqt@nvidia.com>
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        "David S. Miller" <davem@davemloft.net>,
        Jesse Brandeburg <jesse.brandeburg@intel.com>,
        Lukasz Czapnik <lukasz.czapnik@intel.com>,
        Marcin Kubiak <marcin.kubiak@intel.com>,
        Michal Kubiak <michal.kubiak@intel.com>,
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From:   David Ahern <dsahern@gmail.com>
Message-ID: <4b2358e1-a802-b0ab-129d-1432f49c46ec@gmail.com>
Date:   Wed, 4 Aug 2021 18:43:19 -0600
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On 8/4/21 12:27 PM, Saeed Mahameed wrote:
> 
>> I just ran some quick tests with my setup and measured about 1.2%
>> worst
> 
> 1.2% is a lot ! what was the test ? what is the change ?

I did say "quick test ... not exhaustive" and it was definitely
eyeballing a pps change over a small time window.

If multiple counters are bumped 20-25 million times a second (e.g. XDP
drop case), how measurable is it? I was just trying to ballpark the
overhead - 1%, 5%, more? If it is <~ 1% then there is no performance
argument in which case let's do the right thing for users - export via
existing APIs.