linux-kernel - Re: [PATCH net-next v2 3/3] net: stmmac: Optimize cache prefetch in RX path

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Message-ID: <20250114182000.4ca2c433@kernel.org>
Date: Tue, 14 Jan 2025 18:20:00 -0800
From: Jakub Kicinski <kuba@...nel.org>
To: Joe Damato <jdamato@...tly.com>
Cc: Furong Xu <0x1207@...il.com>, netdev@...r.kernel.org,
 linux-stm32@...md-mailman.stormreply.com,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 Alexander Lobakin <aleksander.lobakin@...el.com>, Andrew Lunn
 <andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Maxime
 Coquelin <mcoquelin.stm32@...il.com>, xfr@...look.com
Subject: Re: [PATCH net-next v2 3/3] net: stmmac: Optimize cache prefetch in
 RX path

On Tue, 14 Jan 2025 15:31:05 -0800 Joe Damato wrote:
> > @@ -5525,6 +5521,7 @@ static int stmmac_rx(struct stmmac_priv *priv, int limit, u32 queue)
> >  
> >  			dma_sync_single_for_cpu(priv->device, buf->addr,
> >  						buf1_len, dma_dir);
> > +			prefetch(page_address(buf->page) + buf->page_offset);  
> 
> Minor nit: I've seen in other drivers authors using net_prefetch.
> Probably not worth a re-roll just for something this minor.

Let's respin. I don't know how likely stmmac is to be integrated into
an SoC with 64B cachelines these days, but since you caught this - 
why not potentially save someone from investigating this later..
-- 
pw-bot: cr