From mboxrd@z Thu Jan 1 00:00:00 1970 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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 2CD73C4332B for ; Fri, 20 Mar 2020 04:29:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F117D20722 for ; Fri, 20 Mar 2020 04:29:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727107AbgCTE3w (ORCPT ); Fri, 20 Mar 2020 00:29:52 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:46824 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725996AbgCTE3v (ORCPT ); Fri, 20 Mar 2020 00:29:51 -0400 Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 6CFA615909F2F; Thu, 19 Mar 2020 21:29:51 -0700 (PDT) Date: Thu, 19 Mar 2020 21:29:50 -0700 (PDT) Message-Id: <20200319.212950.742799321773945249.davem@davemloft.net> To: rahul.lakkireddy@chelsio.com Cc: netdev@vger.kernel.org, nirranjan@chelsio.com, vishal@chelsio.com, dt@chelsio.com Subject: Re: [PATCH net] cxgb4: fix throughput drop during Tx backpressure From: David Miller In-Reply-To: <1584639490-27208-1-git-send-email-rahul.lakkireddy@chelsio.com> References: <1584639490-27208-1-git-send-email-rahul.lakkireddy@chelsio.com> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 19 Mar 2020 21:29:51 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Rahul Lakkireddy Date: Thu, 19 Mar 2020 23:08:09 +0530 > 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 Applied and queued up for -stable.