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[87.203.119.87]) by smtp.gmail.com with ESMTPSA id h6sm5250280wmq.5.2021.08.20.02.39.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Aug 2021 02:39:52 -0700 (PDT) Date: Fri, 20 Aug 2021 12:39:45 +0300 From: Ilias Apalodimas To: Yunsheng Lin Cc: davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, hkallweit1@gmail.com Subject: Re: [PATCH net-next v2 2/2] page_pool: optimize the cpu sync operation when DMA mapping Message-ID: References: <1629442611-61547-1-git-send-email-linyunsheng@huawei.com> <1629442611-61547-3-git-send-email-linyunsheng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1629442611-61547-3-git-send-email-linyunsheng@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 20, 2021 at 02:56:51PM +0800, Yunsheng Lin wrote: > If the DMA_ATTR_SKIP_CPU_SYNC is not set, cpu syncing is > also done in dma_map_page_attrs(), so set the attrs according > to pool->p.flags to avoid calling cpu sync function again. Isn't DMA_ATTR_SKIP_CPU_SYNC checked within dma_map_page_attrs() anyway? Regards /Ilias > > Signed-off-by: Yunsheng Lin > --- > net/core/page_pool.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/net/core/page_pool.c b/net/core/page_pool.c > index 1a69784..3df5554 100644 > --- a/net/core/page_pool.c > +++ b/net/core/page_pool.c > @@ -191,8 +191,12 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool, > > static bool page_pool_dma_map(struct page_pool *pool, struct page *page) > { > + unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC; > dma_addr_t dma; > > + if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) > + attrs = 0; > + > /* Setup DMA mapping: use 'struct page' area for storing DMA-addr > * since dma_addr_t can be either 32 or 64 bits and does not always fit > * into page private data (i.e 32bit cpu with 64bit DMA caps) > @@ -200,15 +204,12 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page) > */ > dma = dma_map_page_attrs(pool->p.dev, page, 0, > (PAGE_SIZE << pool->p.order), > - pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); > + pool->p.dma_dir, attrs); > if (dma_mapping_error(pool->p.dev, dma)) > return false; > > page_pool_set_dma_addr(page, dma); > > - if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) > - page_pool_dma_sync_for_device(pool, page, pool->p.max_len); > - > return true; > } > > -- > 2.7.4 >