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Message-ID: <fd2121df712574a240cd56060a138a5686e81b94.camel@kernel.org>
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>,
        Marcin Wojtas <mw@semihalf.com>,
        Russell King <linux@armlinux.org.uk>,
        Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
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        KP Singh <kpsingh@kernel.org>,
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        Sameeh Jubran <sameehj@amazon.com>,
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        Yangbo Lu <yangbo.lu@nxp.com>,
        Michal Kubecek <mkubecek@suse.cz>,
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        Heiner Kallweit <hkallweit1@gmail.com>,
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Date:   Wed, 04 Aug 2021 19:14:09 -0700
In-Reply-To: <4b2358e1-a802-b0ab-129d-1432f49c46ec@gmail.com>
References: <20210803163641.3743-1-alexandr.lobakin@intel.com>
         <20210803163641.3743-4-alexandr.lobakin@intel.com>
         <20210803134900.578b4c37@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
         <ec0aefbc987575d1979f9102d331bd3e8f809824.camel@kernel.org>
         <20210804053650.22aa8a5b@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
         <43e91ce1-0f82-5820-7cac-b42461a0311a@gmail.com>
         <20210804094432.08d0fa86@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
         <d21933cb-9d24-9bdd-cf18-e5077796ddf7@gmail.com>
         <11091d33ff7803257e38ee921e4ba9597acfccfc.camel@kernel.org>
         <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 !