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[24.6.151.244]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70d1dbfe395sm2640504b3a.218.2024.07.22.09.17.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jul 2024 09:17:34 -0700 (PDT) Date: Mon, 22 Jul 2024 09:17:31 -0700 From: Joe Damato To: Elad Yifee Cc: daniel@makrotopia.org, Felix Fietkau , Sean Wang , Mark Lee , Lorenzo Bianconi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, bpf@vger.kernel.org Subject: Re: [PATCH net-next RFC] net: ethernet: mtk_eth_soc: use prefetch methods Message-ID: Mail-Followup-To: Joe Damato , Elad Yifee , daniel@makrotopia.org, Felix Fietkau , Sean Wang , Mark Lee , Lorenzo Bianconi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, bpf@vger.kernel.org References: <20240720164621.1983-1-eladwf@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240720164621.1983-1-eladwf@gmail.com> On Sat, Jul 20, 2024 at 07:46:18PM +0300, Elad Yifee wrote: > Utilize kernel prefetch methods for faster cache line access. > This change boosts driver performance, > allowing the CPU to handle about 5% more packets/sec. Nit: It'd be great to see before/after numbers and/or an explanation of how you measured this in the commit message. > Signed-off-by: Elad Yifee > --- > drivers/net/ethernet/mediatek/mtk_eth_soc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c > index 0cc2dd85652f..1a0704166103 100644 > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c > @@ -1963,6 +1963,7 @@ static u32 mtk_xdp_run(struct mtk_eth *eth, struct mtk_rx_ring *ring, > if (!prog) > goto out; > > + prefetchw(xdp->data_hard_start); Is there any reason to mix net_prefetch (as you have below) with prefetch and prefetchw ? IMHO: you should consider using net_prefetch and net_prefetchw everywhere instead of using both in your code. > act = bpf_prog_run_xdp(prog, xdp); > switch (act) { > case XDP_PASS: > @@ -2039,7 +2040,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, > idx = NEXT_DESP_IDX(ring->calc_idx, ring->dma_size); > rxd = ring->dma + idx * eth->soc->rx.desc_size; > data = ring->data[idx]; > - > + prefetch(rxd); Maybe net_prefetch instead, as mentioned above? > if (!mtk_rx_get_desc(eth, &trxd, rxd)) > break; > > @@ -2105,6 +2106,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, > if (ret != XDP_PASS) > goto skip_rx; > > + net_prefetch(xdp.data_meta); > skb = build_skb(data, PAGE_SIZE); > if (unlikely(!skb)) { > page_pool_put_full_page(ring->page_pool, > @@ -2113,6 +2115,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, > goto skip_rx; > } > > + prefetchw(skb->data); Maybe net_prefetchw instead, as mentioned above? > skb_reserve(skb, xdp.data - xdp.data_hard_start); > skb_put(skb, xdp.data_end - xdp.data); > skb_mark_for_recycle(skb); > @@ -2143,6 +2146,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, > dma_unmap_single(eth->dma_dev, ((u64)trxd.rxd1 | addr64), > ring->buf_size, DMA_FROM_DEVICE); > > + net_prefetch(data); > skb = build_skb(data, ring->frag_size); > if (unlikely(!skb)) { > netdev->stats.rx_dropped++; > @@ -2150,6 +2154,7 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget, > goto skip_rx; > } > > + prefetchw(skb->data); Maybe net_prefetchw instead, as mentioned above?