[...]
> Hi Lore,
Hi Sujuan,
>
> we love your patch, but we have another patch to avoid memory
> fragmentation by duplicating the rx skb after mt76_dma_dequeue(). it
> requires mt76_get_rxwi() be placed before page_frag_alloc().
>
> the below patch(need rebase) will be sent after the current patch is
> accepted.
>
> --- a/drivers/net/wireless/mediatek/mt76/dma.c
> +++ b/drivers/net/wireless/mediatek/mt76/dma.c
> @@ -386,9 +386,11 @@ mt76_dma_get_buf(struct mt76_dev *dev, struct
> mt76_queue *q, int idx,
> SKB_WITH_OVERHEAD(q->buf_size),
> DMA_FROM_DEVICE);
>
> - buf = t->ptr;
> + buf = page_frag_alloc(&q->rx_page, q->buf_size,
> GFP_ATOMIC);
> + if (!buf)
> + return NULL;
> + memcpy(buf, t->ptr, SKB_WITH_OVERHEAD(q->buf_size));
We this approach we still need to allocate the buffer (in mt76_dma_get_buf()
instead of mt76_dma_rx_fill()) but we need even to copy the full buffer that
can be pretty expensive instead of relying on the DMA, so I would avoid this
approach.
Regards,
Lorenzo
> t->dma_addr = 0;
> - t->ptr = NULL;
>
> mt76_put_rxwi(dev, t);
>
> @@ -569,6 +571,7 @@ mt76_dma_rx_fill(struct mt76_dev *dev, struct
> mt76_queue *q)
> while (q->queued < q->ndesc - 1) {
> struct mt76_txwi_cache *t = NULL;
> struct mt76_queue_buf qbuf;
> + bool skip_alloc = false;
> void *buf = NULL;
>
> if ((q->flags & MT_QFLAG_WED) &&
> @@ -576,11 +579,19 @@ mt76_dma_rx_fill(struct mt76_dev *dev, struct
> mt76_queue *q)
> t = mt76_get_rxwi(dev);
> if (!t)
> break;
> +
> + if (t->ptr) {
> + skip_alloc = true;
> + buf = t->ptr;
> + }
> }
>
> - buf = page_frag_alloc(&q->rx_page, q->buf_size,
> GFP_ATOMIC);
> - if (!buf)
> - break;
> + if (!skip_alloc) {
> + buf = page_frag_alloc(&q->rx_page, q->buf_size,
> + GFP_ATOMIC);
> + if (!buf)
> + break;
> + }
>
> addr = dma_map_single(dev->dma_dev, buf, len,
> DMA_FROM_DEVICE);
> if (unlikely(dma_mapping_error(dev->dma_dev, addr))) {
> --
> 2.18.0
>
> > > --
> > > 2.18.0
> > >
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