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Subject: Re: [PATCH net-next 03/21] ethtool, stats: introduce standard XDP
 statistics
From:   Saeed Mahameed <saeed@kernel.org>
To:     David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
        Tariq Toukan <ttoukan.linux@gmail.com>,
        Tariq Toukan <tariqt@nvidia.com>
Cc:     Alexander Lobakin <alexandr.lobakin@intel.com>,
        "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>,
        Michal Swiatkowski <michal.swiatkowski@intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Netanel Belgazal <netanel@amazon.com>,
        Arthur Kiyanovski <akiyano@amazon.com>,
        Guy Tzalik <gtzalik@amazon.com>,
        Saeed Bishara <saeedb@amazon.com>,
        Ioana Ciornei <ioana.ciornei@nxp.com>,
        Claudiu Manoil <claudiu.manoil@nxp.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
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Date:   Wed, 04 Aug 2021 19:14:09 -0700
In-Reply-To: <4b2358e1-a802-b0ab-129d-1432f49c46ec@gmail.com>
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On Wed, 2021-08-04 at 18:43 -0600, David Ahern wrote:
> 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.

from experience I don't believe it can be more than 1% and yes on
existing APIs !