From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jisheng Zhang Subject: Re: [PATCH] net: mvneta: remove useless RX descriptor prefetch Date: Thu, 31 Mar 2016 14:45:37 +0800 Message-ID: <20160331144537.20f04a8c@xhacker> References: <1459406190-2334-1-git-send-email-jszhang@marvell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Cc: , , To: , , Return-path: Received: from mx0a-0016f401.pphosted.com ([67.231.148.174]:40247 "EHLO mx0a-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752873AbcCaGtx (ORCPT ); Thu, 31 Mar 2016 02:49:53 -0400 In-Reply-To: <1459406190-2334-1-git-send-email-jszhang@marvell.com> Sender: netdev-owner@vger.kernel.org List-ID: Hi, + linux arm kernel On Thu, 31 Mar 2016 14:36:30 +0800 Jisheng Zhang wrote: > The rx descriptors are allocated using dma_alloc_coherent, so prefetch > doesn't really happen at all. This is for RFC, I'm sorry to send it without changing its title -- s/PATCH/RFC. I'm not sure whether there's any benefit to prefetch on space allocated from dma_alloc_coherent. Thanks > > Signed-off-by: Jisheng Zhang > --- > drivers/net/ethernet/marvell/mvneta.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c > index 5880871..6c09a27 100644 > --- a/drivers/net/ethernet/marvell/mvneta.c > +++ b/drivers/net/ethernet/marvell/mvneta.c > @@ -757,7 +757,6 @@ mvneta_rxq_next_desc_get(struct mvneta_rx_queue *rxq) > int rx_desc = rxq->next_desc_to_proc; > > rxq->next_desc_to_proc = MVNETA_QUEUE_NEXT_DESC(rxq, rx_desc); > - prefetch(rxq->descs + rxq->next_desc_to_proc); > return rxq->descs + rx_desc; > } >