netdev - Re: [PATCH net-next v1] page_pool: check for dma_sync

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Message-ID: <20241011084924.1fa2eb7d@kernel.org>
Date: Fri, 11 Oct 2024 08:49:24 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Furong Xu <0x1207@...il.com>
Cc: Yunsheng Lin <linyunsheng@...wei.com>, Ilias Apalodimas
 <ilias.apalodimas@...aro.org>, <netdev@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, "Jesper Dangaard Brouer" <hawk@...nel.org>,
 "David S. Miller" <davem@...emloft.net>, "Eric Dumazet"
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, <xfr@...look.com>
Subject: Re: [PATCH net-next v1] page_pool: check for dma_sync_size earlier

On Fri, 11 Oct 2024 17:26:05 +0800 Furong Xu wrote:
> > In order to support the above use case, it seems there might be two
> > options here:
> > 1. Driver calls page_pool_create() without PP_FLAG_DMA_SYNC_DEV and
> >    handle the dma sync itself.
> > 2. Page_pool may provides a non-dma-sync version of page_pool_put_page()
> >    API even when Driver calls page_pool_create() with PP_FLAG_DMA_SYNC_DEV.
> > 
> > Maybe option 2 is better one in the longer term as it may provide some
> > flexibility for the user and enable removing of the DMA_SYNC_DEV in the
> > future?  
> 
> What is your opinion about this?

I think your patch is fine, but it's a micro optimization so you need 
to provide some measurement data to show how much of a performance
improvement you're getting.