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Miller" , Eric Dumazet , Jakub Kicinski , "Paolo Abeni" , Maxime Coquelin , Subject: Re: [PATCH net-next v1 3/3] net: stmmac: Optimize cache prefetch in RX path Message-ID: <20250113203710.000033dc@gmail.com> In-Reply-To: References: X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 13 Jan 2025 13:10:46 +0100, Alexander Lobakin wrote: > > @@ -5596,6 +5593,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue) > > } else if (buf1_len) { > > dma_sync_single_for_cpu(priv->device, buf->addr, > > buf1_len, dma_dir); > > + prefetch(page_address(buf->page) + buf->page_offset); > > skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, > > buf->page, buf->page_offset, buf1_len, > > priv->dma_conf.dma_buf_sz); > > Are you sure you need to prefetch frags as well? I'd say this is a waste > of cycles, as the kernel core stack barely looks at payload... > Probably prefetching only header buffers would be enough. > Yes, do not prefetch for frags is more reasonable. Thanks! pw-bot: changes-requested