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Date:   Tue, 23 Mar 2021 18:10:46 +0200
From:   Ilias Apalodimas <ilias.apalodimas@linaro.org>
To:     Jesper Dangaard Brouer <jbrouer@redhat.com>
Cc:     Alexander Lobakin <alobakin@pm.me>,
        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>,
        David Ahern <dsahern@gmail.com>,
        Saeed Mahameed <saeed@kernel.org>, Andrew Lunn <andrew@lunn.ch>
Subject: Re: [PATCH net-next 0/6] page_pool: recycle buffers
Message-ID: <YFoTBm0mJ4GyuHb6@enceladus>
References: <20210322170301.26017-1-mcroce@linux.microsoft.com>
 <20210323154112.131110-1-alobakin@pm.me>
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On Tue, Mar 23, 2021 at 05:04:47PM +0100, Jesper Dangaard Brouer wrote:
> On Tue, 23 Mar 2021 17:47:46 +0200
> Ilias Apalodimas <ilias.apalodimas@linaro.org> wrote:
> 
> > On Tue, Mar 23, 2021 at 03:41:23PM +0000, Alexander Lobakin wrote:
> > > From: Matteo Croce <mcroce@linux.microsoft.com>
> > > Date: Mon, 22 Mar 2021 18:02:55 +0100
> > >   
> > > > 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.
> > > >
> > > > 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.
> > > >
> > > > Ilias Apalodimas (2):
> > > >   page_pool: DMA handling and allow to recycles frames via SKB
> > > >   net: change users of __skb_frag_unref() and add an extra argument
> > > >
> > > > Jesper Dangaard Brouer (1):
> > > >   xdp: reduce size of struct xdp_mem_info
> > > >
> > > > Matteo Croce (3):
> > > >   mm: add a signature in struct page
> > > >   mvpp2: recycle buffers
> > > >   mvneta: recycle buffers
> > > >
> > > >  .../chelsio/inline_crypto/ch_ktls/chcr_ktls.c |  2 +-
> > > >  drivers/net/ethernet/marvell/mvneta.c         |  4 +-
> > > >  .../net/ethernet/marvell/mvpp2/mvpp2_main.c   | 17 +++----
> > > >  drivers/net/ethernet/marvell/sky2.c           |  2 +-
> > > >  drivers/net/ethernet/mellanox/mlx4/en_rx.c    |  2 +-
> > > >  include/linux/mm_types.h                      |  1 +
> > > >  include/linux/skbuff.h                        | 33 +++++++++++--
> > > >  include/net/page_pool.h                       | 15 ++++++
> > > >  include/net/xdp.h                             |  5 +-
> > > >  net/core/page_pool.c                          | 47 +++++++++++++++++++
> > > >  net/core/skbuff.c                             | 20 +++++++-
> > > >  net/core/xdp.c                                | 14 ++++--
> > > >  net/tls/tls_device.c                          |  2 +-
> > > >  13 files changed, 138 insertions(+), 26 deletions(-)  
> > > 
> > > Just for the reference, I've performed some tests on 1G SoC NIC with
> > > this patchset on, here's direct link: [0]
> > >   
> > 
> > Thanks for the testing!
> > Any chance you can get a perf measurement on this?
> 
> I guess you mean perf-report (--stdio) output, right?
> 

Yea, 
As hinted below, I am just trying to figure out if on Alexander's platform the
cost of syncing, is bigger that free-allocate. I remember one armv7 were that
was the case. 

> > Is DMA syncing taking a substantial amount of your cpu usage?
> 
> (+1 this is an important question)
>  
> > > 
> > > [0] https://lore.kernel.org/netdev/20210323153550.130385-1-alobakin@pm.me
> > > 
> 
> -- 
> Best regards,
>   Jesper Dangaard Brouer
>   MSc.CS, Principal Kernel Engineer at Red Hat
>   LinkedIn: http://www.linkedin.com/in/brouer
>