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Date:   Tue, 23 Mar 2021 17:03:43 +0200
From:   Ilias Apalodimas <ilias.apalodimas@linaro.org>
To:     David Ahern <dsahern@gmail.com>
Cc:     Matteo Croce <mcroce@linux.microsoft.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Lorenzo Bianconi <lorenzo@kernel.org>,
        Saeed Mahameed <saeedm@nvidia.com>,
        Saeed Mahameed <saeed@kernel.org>, Andrew Lunn <andrew@lunn.ch>
Subject: Re: [PATCH net-next 0/6] page_pool: recycle buffers
Message-ID: <YFoDT90swFCXpYLB@enceladus>
References: <20210322170301.26017-1-mcroce@linux.microsoft.com>
 <f5ef2e4f-fcba-2e06-86ec-17522744b6a8@gmail.com>
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Hi David, 

On Tue, Mar 23, 2021 at 08:57:57AM -0600, David Ahern wrote:
> On 3/22/21 11:02 AM, Matteo Croce wrote:
> > From: Matteo Croce <mcroce@microsoft.com>
> > 
> > This series enables recycling of the buffers allocated with the page_pool API.
> > The first two patches are just prerequisite to save space in a struct and
> > avoid recycling pages allocated with other API.
> > Patch 2 was based on a previous idea from Jonathan Lemon.
> > 
> > The third one is the real recycling, 4 fixes the compilation of __skb_frag_unref
> > users, and 5,6 enable the recycling on two drivers.
> 
> patch 4 should be folded into 3; each patch should build without errors.
> 

Yes 

> > 
> > In the last two patches I reported the improvement I have with the series.
> > 
> > The recycling as is can't be used with drivers like mlx5 which do page split,
> > but this is documented in a comment.
> > In the future, a refcount can be used so to support mlx5 with no changes.
> 
> Is the end goal of the page_pool changes to remove driver private caches?
> 
> 

Yes. The patchset doesn't currently support that , because all the >10gbit
interfaces split the page and we don't account for that. We should be able to 
extend it though and account for that.  I don't have any hardware
(Intel/mlx) available, but I'll be happy to talk to anyone that does and
figure out a way to support those cards properly.


Cheers
/Ilias