netdev - Re: [PATCH 1/3, net-next] net: netsec: Use page

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Date:   Fri, 28 Jun 2019 09:43:43 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     brouer@...hat.com
Cc:     ilias.apalodimas@...aro.org, netdev@...r.kernel.org,
        jaswinder.singh@...aro.org, ard.biesheuvel@...aro.org,
        bjorn.topel@...el.com, magnus.karlsson@...el.com,
        daniel@...earbox.net, ast@...nel.org,
        makita.toshiaki@....ntt.co.jp, jakub.kicinski@...ronome.com,
        john.fastabend@...il.com, maciejromanfijalkowski@...il.com
Subject: Re: [PATCH 1/3, net-next] net: netsec: Use page_pool API

From: Jesper Dangaard Brouer <brouer@...hat.com>
Date: Fri, 28 Jun 2019 15:04:34 +0200

> On Fri, 28 Jun 2019 13:39:13 +0300
> Ilias Apalodimas <ilias.apalodimas@...aro.org> wrote:
> 
>> Use page_pool and it's DMA mapping capabilities for Rx buffers instead
>> of netdev/napi_alloc_frag()
>> 
>> Although this will result in a slight performance penalty on small sized
>> packets (~10%) the use of the API will allow to easily add XDP support.
>> The penalty won't be visible in network testing i.e ipef/netperf etc, it
>> only happens during raw packet drops.
>> Furthermore we intend to add recycling capabilities on the API
>> in the future. Once the recycling is added the performance penalty will
>> go away.
>> The only 'real' penalty is the slightly increased memory usage, since we
>> now allocate a page per packet instead of the amount of bytes we need +
>> skb metadata (difference is roughly 2kb per packet).
>> With a minimum of 4BG of RAM on the only SoC that has this NIC the
>> extra memory usage is negligible (a bit more on 64K pages)
>> 
>> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@...aro.org>
>> ---
>>  drivers/net/ethernet/socionext/Kconfig  |   1 +
>>  drivers/net/ethernet/socionext/netsec.c | 121 +++++++++++++++---------
>>  2 files changed, 75 insertions(+), 47 deletions(-)
> 
> Acked-by: Jesper Dangaard Brouer <brouer@...hat.com>

Jesper this is confusing, you just asked if the code needs to be moved
around to be correct and then right now immediately afterwards you ACK
the patch.