From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sinan Kaya Date: Fri, 23 Mar 2018 14:52:56 -0400 Subject: [Intel-wired-lan] [PATCH v7 3/7] igbvf: eliminate duplicate barriers on weakly-ordered archs In-Reply-To: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> References: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> Message-ID: <1521831180-25014-4-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/net/ethernet/intel/igbvf/netdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c index fa07876..df2283b 100644 --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -252,7 +252,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, adapter->hw.hw_addr + rx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail); } } @@ -2298,7 +2298,7 @@ static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; - writel(i, adapter->hw.hw_addr + tx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + tx_ring->tail); /* we need this if more than one processor can write to our tail * at a time, it synchronizes IO on IA64/Altix systems */ -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sinan Kaya Subject: [PATCH v7 3/7] igbvf: eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 14:52:56 -0400 Message-ID: <1521831180-25014-4-git-send-email-okaya@codeaurora.org> References: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: jeffrey.t.kirsher@intel.com Cc: sulrich@codeaurora.org, netdev@vger.kernel.org, timur@codeaurora.org, linux-kernel@vger.kernel.org, Sinan Kaya , intel-wired-lan@lists.osuosl.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org List-Id: linux-arm-msm@vger.kernel.org Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/net/ethernet/intel/igbvf/netdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c index fa07876..df2283b 100644 --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -252,7 +252,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, adapter->hw.hw_addr + rx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail); } } @@ -2298,7 +2298,7 @@ static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; - writel(i, adapter->hw.hw_addr + tx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + tx_ring->tail); /* we need this if more than one processor can write to our tail * at a time, it synchronizes IO on IA64/Altix systems */ -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 From: okaya@codeaurora.org (Sinan Kaya) Date: Fri, 23 Mar 2018 14:52:56 -0400 Subject: [PATCH v7 3/7] igbvf: eliminate duplicate barriers on weakly-ordered archs In-Reply-To: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> References: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> Message-ID: <1521831180-25014-4-git-send-email-okaya@codeaurora.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/net/ethernet/intel/igbvf/netdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c index fa07876..df2283b 100644 --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -252,7 +252,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, adapter->hw.hw_addr + rx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail); } } @@ -2298,7 +2298,7 @@ static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; - writel(i, adapter->hw.hw_addr + tx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + tx_ring->tail); /* we need this if more than one processor can write to our tail * at a time, it synchronizes IO on IA64/Altix systems */ -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752593AbeCWSzF (ORCPT ); Fri, 23 Mar 2018 14:55:05 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:46322 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751668AbeCWSxJ (ORCPT ); Fri, 23 Mar 2018 14:53:09 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 11FD960F61 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya To: jeffrey.t.kirsher@intel.com Cc: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH v7 3/7] igbvf: eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 14:52:56 -0400 Message-Id: <1521831180-25014-4-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> References: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Code includes wmb() followed by writel(). writel() already has a barrier on some architectures like arm64. This ends up CPU observing two barriers back to back before executing the register write. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya --- drivers/net/ethernet/intel/igbvf/netdev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c index fa07876..df2283b 100644 --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -252,7 +252,7 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, adapter->hw.hw_addr + rx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + rx_ring->tail); } } @@ -2298,7 +2298,7 @@ static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; - writel(i, adapter->hw.hw_addr + tx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + tx_ring->tail); /* we need this if more than one processor can write to our tail * at a time, it synchronizes IO on IA64/Altix systems */ -- 2.7.4