From patchwork Tue Feb 9 02:23:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tony Nguyen X-Patchwork-Id: 379873 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DECF7C433E6 for ; Tue, 9 Feb 2021 02:24:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D79A64E76 for ; Tue, 9 Feb 2021 02:24:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230355AbhBICYj (ORCPT ); Mon, 8 Feb 2021 21:24:39 -0500 Received: from mga09.intel.com ([134.134.136.24]:15909 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229975AbhBICYR (ORCPT ); Mon, 8 Feb 2021 21:24:17 -0500 IronPort-SDR: 5ayyQgLqbOxXP13e0G3ZwEneVsSiD6wgQz9DKX4yhOcrHdmFbiGcaseOIXPNBidCw7pKp1PMAT 4oO1fgwdv3FQ== X-IronPort-AV: E=McAfee;i="6000,8403,9889"; a="181960304" X-IronPort-AV: E=Sophos;i="5.81,163,1610438400"; d="scan'208";a="181960304" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Feb 2021 18:22:48 -0800 IronPort-SDR: 8xakOXaDiQNVDghUqaw7maAG8l04QGS24vCmCJyFOAJil1YeSM6nHOQlnb8vTrGI7F6syYjCK0 h6CgnTI5V7rg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,163,1610438400"; d="scan'208";a="359003691" Received: from anguy11-desk2.jf.intel.com ([10.166.244.147]) by orsmga003.jf.intel.com with ESMTP; 08 Feb 2021 18:22:45 -0800 From: Tony Nguyen To: davem@davemloft.net, kuba@kernel.org Cc: Cristian Dumitrescu , netdev@vger.kernel.org, sassmann@redhat.com, anthony.l.nguyen@intel.com, bjorn.topel@intel.com, maciej.fijalkowski@intel.com, magnus.karlsson@intel.com, Kiran Bhandare Subject: [PATCH net-next v2 1/5] i40e: remove unnecessary memory writes of the next to clean pointer Date: Mon, 8 Feb 2021 18:23:19 -0800 Message-Id: <20210209022323.2440775-2-anthony.l.nguyen@intel.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210209022323.2440775-1-anthony.l.nguyen@intel.com> References: <20210209022323.2440775-1-anthony.l.nguyen@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Cristian Dumitrescu For performance reasons, avoid writing the ring next-to-clean pointer value back to memory on every update, as it is not really necessary. Instead, simply read it at initialization into a local copy, update the local copy as necessary and write the local copy back to memory after the last update. Signed-off-by: Cristian Dumitrescu Tested-by: Kiran Bhandare Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/i40e/i40e_xsk.c | 30 ++++++++-------------- 1 file changed, 11 insertions(+), 19 deletions(-) diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c b/drivers/net/ethernet/intel/i40e/i40e_xsk.c index 492ce213208d..87d43407653c 100644 --- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c +++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c @@ -261,18 +261,6 @@ static struct sk_buff *i40e_construct_skb_zc(struct i40e_ring *rx_ring, return skb; } -/** - * i40e_inc_ntc: Advance the next_to_clean index - * @rx_ring: Rx ring - **/ -static void i40e_inc_ntc(struct i40e_ring *rx_ring) -{ - u32 ntc = rx_ring->next_to_clean + 1; - - ntc = (ntc < rx_ring->count) ? ntc : 0; - rx_ring->next_to_clean = ntc; -} - /** * i40e_clean_rx_irq_zc - Consumes Rx packets from the hardware ring * @rx_ring: Rx ring @@ -284,6 +272,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) { unsigned int total_rx_bytes = 0, total_rx_packets = 0; u16 cleaned_count = I40E_DESC_UNUSED(rx_ring); + u16 next_to_clean = rx_ring->next_to_clean; + u16 count_mask = rx_ring->count - 1; unsigned int xdp_res, xdp_xmit = 0; bool failure = false; struct sk_buff *skb; @@ -294,7 +284,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) unsigned int size; u64 qword; - rx_desc = I40E_RX_DESC(rx_ring, rx_ring->next_to_clean); + rx_desc = I40E_RX_DESC(rx_ring, next_to_clean); qword = le64_to_cpu(rx_desc->wb.qword1.status_error_len); /* This memory barrier is needed to keep us from reading @@ -307,11 +297,11 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) i40e_clean_programming_status(rx_ring, rx_desc->raw.qword[0], qword); - bi = i40e_rx_bi(rx_ring, rx_ring->next_to_clean); + bi = i40e_rx_bi(rx_ring, next_to_clean); xsk_buff_free(*bi); *bi = NULL; cleaned_count++; - i40e_inc_ntc(rx_ring); + next_to_clean = (next_to_clean + 1) & count_mask; continue; } @@ -320,7 +310,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) if (!size) break; - bi = i40e_rx_bi(rx_ring, rx_ring->next_to_clean); + bi = i40e_rx_bi(rx_ring, next_to_clean); (*bi)->data_end = (*bi)->data + size; xsk_buff_dma_sync_for_cpu(*bi, rx_ring->xsk_pool); @@ -336,7 +326,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) total_rx_packets++; cleaned_count++; - i40e_inc_ntc(rx_ring); + next_to_clean = (next_to_clean + 1) & count_mask; continue; } @@ -355,7 +345,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) *bi = NULL; cleaned_count++; - i40e_inc_ntc(rx_ring); + next_to_clean = (next_to_clean + 1) & count_mask; if (eth_skb_pad(skb)) continue; @@ -367,6 +357,8 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) napi_gro_receive(&rx_ring->q_vector->napi, skb); } + rx_ring->next_to_clean = next_to_clean; + if (cleaned_count >= I40E_RX_BUFFER_WRITE) failure = !i40e_alloc_rx_buffers_zc(rx_ring, cleaned_count); @@ -374,7 +366,7 @@ int i40e_clean_rx_irq_zc(struct i40e_ring *rx_ring, int budget) i40e_update_rx_stats(rx_ring, total_rx_bytes, total_rx_packets); if (xsk_uses_need_wakeup(rx_ring->xsk_pool)) { - if (failure || rx_ring->next_to_clean == rx_ring->next_to_use) + if (failure || next_to_clean == rx_ring->next_to_use) xsk_set_rx_need_wakeup(rx_ring->xsk_pool); else xsk_clear_rx_need_wakeup(rx_ring->xsk_pool);