From patchwork Thu Mar 19 17:38:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rahul Lakkireddy X-Patchwork-Id: 1258354 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=chelsio.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48jvY519vBz9sRN for ; Fri, 20 Mar 2020 04:49:13 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727810AbgCSRtM (ORCPT ); Thu, 19 Mar 2020 13:49:12 -0400 Received: from stargate.chelsio.com ([12.32.117.8]:65110 "EHLO stargate.chelsio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726934AbgCSRtM (ORCPT ); Thu, 19 Mar 2020 13:49:12 -0400 Received: from localhost (scalar.blr.asicdesigners.com [10.193.185.94]) by stargate.chelsio.com (8.13.8/8.13.8) with ESMTP id 02JHn86S015047; Thu, 19 Mar 2020 10:49:09 -0700 From: Rahul Lakkireddy To: netdev@vger.kernel.org Cc: davem@davemloft.net, nirranjan@chelsio.com, vishal@chelsio.com, dt@chelsio.com Subject: [PATCH net] cxgb4: fix Txq restart check during backpressure Date: Thu, 19 Mar 2020 23:08:10 +0530 Message-Id: <1584639490-27208-2-git-send-email-rahul.lakkireddy@chelsio.com> X-Mailer: git-send-email 2.5.3 In-Reply-To: <1584639490-27208-1-git-send-email-rahul.lakkireddy@chelsio.com> References: <1584639490-27208-1-git-send-email-rahul.lakkireddy@chelsio.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Driver reclaims descriptors in much smaller batches, even if hardware indicates more to reclaim, during backpressure. So, fix the check to restart the Txq during backpressure, by looking at how many descriptors hardware had indicated to reclaim, and not on how many descriptors that driver had actually reclaimed. Once the Txq is restarted, driver will reclaim even more descriptors when Tx path is entered again. Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer") Signed-off-by: Rahul Lakkireddy --- drivers/net/ethernet/chelsio/cxgb4/sge.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/chelsio/cxgb4/sge.c b/drivers/net/ethernet/chelsio/cxgb4/sge.c index c816837fbd85..cab3d17e0e1a 100644 --- a/drivers/net/ethernet/chelsio/cxgb4/sge.c +++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c @@ -1307,8 +1307,9 @@ static inline void *write_tso_wr(struct adapter *adap, struct sk_buff *skb, int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq, int maxreclaim) { + unsigned int reclaimed, hw_cidx; struct sge_txq *q = &eq->q; - unsigned int reclaimed; + int hw_in_use; if (!q->in_use || !__netif_tx_trylock(eq->txq)) return 0; @@ -1316,12 +1317,17 @@ int t4_sge_eth_txq_egress_update(struct adapter *adap, struct sge_eth_txq *eq, /* Reclaim pending completed TX Descriptors. */ reclaimed = reclaim_completed_tx(adap, &eq->q, maxreclaim, true); + hw_cidx = ntohs(READ_ONCE(q->stat->cidx)); + hw_in_use = q->pidx - hw_cidx; + if (hw_in_use < 0) + hw_in_use += q->size; + /* If the TX Queue is currently stopped and there's now more than half * the queue available, restart it. Otherwise bail out since the rest * of what we want do here is with the possibility of shipping any * currently buffered Coalesced TX Work Request. */ - if (netif_tx_queue_stopped(eq->txq) && txq_avail(q) > (q->size / 2)) { + if (netif_tx_queue_stopped(eq->txq) && hw_in_use < (q->size / 2)) { netif_tx_wake_queue(eq->txq); eq->q.restarts++; }