From patchwork Tue Mar 31 08:57:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 228697 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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 8F377C2D0EE for ; Tue, 31 Mar 2020 09:02:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 670E1208E0 for ; Tue, 31 Mar 2020 09:02:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585645369; bh=OvGtAQjeaDs1YhaORxbUn3vpc64Qir1ZvdQzQQz/FRk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=SPHCmhut5v9I/WG0xCez/mvQQmrgkw7cXITQCHpz8pUahLtGFTpzY611/J/OqNg7c 8i/5mS50J5HkoXNxPCk8hxxTUTxAAD8at7FWhA9RtLOU9muflilici0t662ZMsH+Js BQYHdidS+OEx24ecPc8PvtlGy4KUkNil+W5mPwnk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730445AbgCaJCs (ORCPT ); Tue, 31 Mar 2020 05:02:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:42348 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726299AbgCaJCo (ORCPT ); Tue, 31 Mar 2020 05:02:44 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6C67A20B80; Tue, 31 Mar 2020 09:02:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585645363; bh=OvGtAQjeaDs1YhaORxbUn3vpc64Qir1ZvdQzQQz/FRk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MvlA6GnScHKppjJ6lkQ1xYjjlABwDalhQQ71a6/DX5hGo5QiaUsr6xgG1OwR8czxM 3UhvlPWlBELhXEZBwf1KV1D5glSpFT9bFaJAW+VyU5IFGr40/0jXpUXABmXF4fw2LR 5ay5DeN13DnP10aDtZ5cLi7R8f71Jxe/yPMVqPkM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rahul Lakkireddy , "David S. Miller" Subject: [PATCH 5.5 008/170] cxgb4: fix throughput drop during Tx backpressure Date: Tue, 31 Mar 2020 10:57:02 +0200 Message-Id: <20200331085425.035642242@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200331085423.990189598@linuxfoundation.org> References: <20200331085423.990189598@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Rahul Lakkireddy [ Upstream commit 7affd80802afb6ca92dba47d768632fbde365241 ] commit 7c3bebc3d868 ("cxgb4: request the TX CIDX updates to status page") reverted back to getting Tx CIDX updates via DMA, instead of interrupts, introduced by commit d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer") However, it missed reverting back several code changes where Tx CIDX updates are not explicitly requested during backpressure when using interrupt mode. These missed changes cause slow recovery during backpressure because the corresponding interrupt no longer comes and hence results in Tx throughput drop. So, revert back these missed code changes, as well, which will allow explicitly requesting Tx CIDX updates when backpressure happens. This enables the corresponding interrupt with Tx CIDX update message to get generated and hence speed up recovery and restore back throughput. Fixes: 7c3bebc3d868 ("cxgb4: request the TX CIDX updates to status page") Fixes: d429005fdf2c ("cxgb4/cxgb4vf: Add support for SGE doorbell queue timer") Signed-off-by: Rahul Lakkireddy Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/chelsio/cxgb4/sge.c | 42 +------------------------------ 1 file changed, 2 insertions(+), 40 deletions(-) --- a/drivers/net/ethernet/chelsio/cxgb4/sge.c +++ b/drivers/net/ethernet/chelsio/cxgb4/sge.c @@ -1486,16 +1486,7 @@ static netdev_tx_t cxgb4_eth_xmit(struct * has opened up. */ eth_txq_stop(q); - - /* If we're using the SGE Doorbell Queue Timer facility, we - * don't need to ask the Firmware to send us Egress Queue CIDX - * Updates: the Hardware will do this automatically. And - * since we send the Ingress Queue CIDX Updates to the - * corresponding Ethernet Response Queue, we'll get them very - * quickly. - */ - if (!q->dbqt) - wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F; + wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F; } wr = (void *)&q->q.desc[q->q.pidx]; @@ -1805,16 +1796,7 @@ static netdev_tx_t cxgb4_vf_eth_xmit(str * has opened up. */ eth_txq_stop(txq); - - /* If we're using the SGE Doorbell Queue Timer facility, we - * don't need to ask the Firmware to send us Egress Queue CIDX - * Updates: the Hardware will do this automatically. And - * since we send the Ingress Queue CIDX Updates to the - * corresponding Ethernet Response Queue, we'll get them very - * quickly. - */ - if (!txq->dbqt) - wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F; + wr_mid |= FW_WR_EQUEQ_F | FW_WR_EQUIQ_F; } /* Start filling in our Work Request. Note that we do _not_ handle @@ -3370,26 +3352,6 @@ static void t4_tx_completion_handler(str } txq = &s->ethtxq[pi->first_qset + rspq->idx]; - - /* We've got the Hardware Consumer Index Update in the Egress Update - * message. If we're using the SGE Doorbell Queue Timer mechanism, - * these Egress Update messages will be our sole CIDX Updates we get - * since we don't want to chew up PCIe bandwidth for both Ingress - * Messages and Status Page writes. However, The code which manages - * reclaiming successfully DMA'ed TX Work Requests uses the CIDX value - * stored in the Status Page at the end of the TX Queue. It's easiest - * to simply copy the CIDX Update value from the Egress Update message - * to the Status Page. Also note that no Endian issues need to be - * considered here since both are Big Endian and we're just copying - * bytes consistently ... - */ - if (txq->dbqt) { - struct cpl_sge_egr_update *egr; - - egr = (struct cpl_sge_egr_update *)rsp; - WRITE_ONCE(txq->q.stat->cidx, egr->cidx); - } - t4_sge_eth_txq_egress_update(adapter, txq, -1); }