linux-kernel - Re: [PATCH net-next v9 7/9] libeth: add Rx buffer management

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Date: Mon, 8 Apr 2024 11:09:44 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Przemek Kitszel <przemyslaw.kitszel@...el.com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Alexander Duyck <alexanderduyck@...com>, Yunsheng Lin
	<linyunsheng@...wei.com>, Jesper Dangaard Brouer <hawk@...nel.org>, "Ilias
 Apalodimas" <ilias.apalodimas@...aro.org>, Christoph Lameter <cl@...ux.com>,
	Vlastimil Babka <vbabka@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>,
	<nex.sw.ncis.osdt.itp.upstreaming@...el.com>, <netdev@...r.kernel.org>,
	<intel-wired-lan@...ts.osuosl.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v9 7/9] libeth: add Rx buffer management

From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
Date: Fri, 5 Apr 2024 12:32:55 +0200

> On 4/4/24 17:44, Alexander Lobakin wrote:
>> Add a couple intuitive helpers to hide Rx buffer implementation details

[...]

>> +struct libeth_fqe {
>> +    struct page        *page;
>> +    u32            offset;
>> +    u32            truesize;
>> +} __aligned_largest;
>> +
>> +/**
>> + * struct libeth_fq - structure representing a buffer queue
>> + * @fp: hotpath part of the structure
>> + * @pp: &page_pool for buffer management
>> + * @fqes: array of Rx buffers
>> + * @truesize: size to allocate per buffer, w/overhead
>> + * @count: number of descriptors/buffers the queue has
>> + * @buf_len: HW-writeable length per each buffer
>> + * @nid: ID of the closest NUMA node with memory
>> + */
>> +struct libeth_fq {
>> +    struct_group_tagged(libeth_fq_fp, fp,
>> +        struct page_pool    *pp;
>> +        struct libeth_fqe    *fqes;
>> +
>> +        u32            truesize;
>> +        u32            count;
>> +    );
>> +
>> +    /* Cold fields */
>> +    u32            buf_len;
>> +    int            nid;
>> +};
> 
> [...]
> 
> Could you please unpack the meaning of `fq` and `fqe` acronyms here?

Rx:

RQ -- receive queue, on which you get Rx DMA complete descriptors
FQ -- fill queue, the one you fill with free buffers
  FQE -- fill queue element, i.e. smth like "iavf_rx_buffer" or whatever

Tx:

SQ -- send queue, the one you fill with buffers to transmit
  SQE -- send queue element, i.e. "iavf_tx_buffer"
CQ -- completion queue, on which you get Tx DMA complete descriptors

XDPSQ, XSkRQ etc. -- same as above, but for XDP / XSk

I know that rxq, txq, bufq, complq is more common since it's been used
for years, but I like these "new" ones more :>

> 
> otherwise the whole series is very good for me, thank you very much!
> 

Thanks,
Olek