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@xxxxxxxxx>
---
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;
+};
[...]
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!
