Messages in this thread | | | Date | Fri, 5 Apr 2024 12:32:55 +0200 | Subject | Re: [PATCH net-next v9 7/9] libeth: add Rx buffer management | From | Przemek Kitszel <> |
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On 4/4/24 17:44, Alexander Lobakin wrote: > Add a couple intuitive helpers to hide Rx buffer implementation details > in the library and not multiplicate it between drivers. The settings are > sorta optimized for 100G+ NICs, but nothing really HW-specific here. > Use the new page_pool_dev_alloc() to dynamically switch between > split-page and full-page modes depending on MTU, page size, required > headroom etc. For example, on x86_64 with the default driver settings > each page is shared between 2 buffers. Turning on XDP (not in this > series) -> increasing headroom requirement pushes truesize out of 2048 > boundary, leading to that each buffer starts getting a full page. > The "ceiling" limit is %PAGE_SIZE, as only order-0 pages are used to > avoid compound overhead. For the above architecture, this means maximum > linear frame size of 3712 w/o XDP. > Not that &libeth_buf_queue is not a complete queue/ring structure for > now, rather a shim, but eventually the libeth-enabled drivers will move > to it, with iavf being the first one. > > Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com> > --- > drivers/net/ethernet/intel/libeth/Kconfig | 1 + > include/net/libeth/rx.h | 117 ++++++++++++++++++++++ > drivers/net/ethernet/intel/libeth/rx.c | 98 ++++++++++++++++++ > 3 files changed, 216 insertions(+) > [...]
> +/** > + * struct libeth_fqe - structure representing an Rx buffer > + * @page: page holding the buffer > + * @offset: offset from the page start (to the headroom) > + * @truesize: total space occupied by the buffer (w/ headroom and tailroom) > + * > + * Depending on the MTU, API switches between one-page-per-frame and shared > + * page model (to conserve memory on bigger-page platforms). In case of the > + * former, @offset is always 0 and @truesize is always ```PAGE_SIZE```. > + */ > +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; > +};
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Could you please unpack the meaning of `fq` and `fqe` acronyms here?
otherwise the whole series is very good for me, thank you very much!
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