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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 29973C433E2 for ; Thu, 3 Sep 2020 08:40:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F33D3205F4 for ; Thu, 3 Sep 2020 08:40:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="gAU2dhcj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728314AbgICIkH (ORCPT ); Thu, 3 Sep 2020 04:40:07 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:55866 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726543AbgICIkG (ORCPT ); Thu, 3 Sep 2020 04:40:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599122405; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nkompj5IxHGnEPikK3tjox7kn9DQzhQmyMUxr6MfduU=; b=gAU2dhcjCXjB9cRCksONNpnCKv4McCDvFKn0UhXVG71jKwCDfgobKQ3PxkBJLrol6bDa+u mjMFORjpWQA+VB4v6ceD690oUlY1B4la6cPduX8OdawuLwAuhbkLGGTLZDzGcw8TIVrPG3 dOSfezF/A9LItZgwmgQAdCA780C6TuE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-326-wYAvPqxcMZWIiuS14GZ_bg-1; Thu, 03 Sep 2020 04:40:00 -0400 X-MC-Unique: wYAvPqxcMZWIiuS14GZ_bg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9CFF58015F6; Thu, 3 Sep 2020 08:39:58 +0000 (UTC) Received: from ovpn-115-2.ams2.redhat.com (ovpn-115-2.ams2.redhat.com [10.36.115.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8309A19C59; Thu, 3 Sep 2020 08:39:55 +0000 (UTC) Message-ID: Subject: Re: Packet gets stuck in NOLOCK pfifo_fast qdisc From: Paolo Abeni To: Cong Wang , Kehuan Feng Cc: Hillf Danton , Jike Song , Josh Hunt , Jonas Bonn , Michael Zhivich , David Miller , John Fastabend , LKML , Netdev Date: Thu, 03 Sep 2020 10:39:54 +0200 In-Reply-To: References: <465a540e-5296-32e7-f6a6-79942dfe2618@netrounds.com> <20200623134259.8197-1-mzhivich@akamai.com> <1849b74f-163c-8cfa-baa5-f653159fefd4@akamai.com> <7fd86d97-6785-0b5f-1e95-92bc1da9df35@netrounds.com> <500b4843cb7c425ea5449fe199095edd5f7feb0c.camel@redhat.com> <25ca46e4-a8c1-1c88-d6a9-603289ff44c3@akamai.com> <20200822032800.16296-1-hdanton@sina.com> <20200825032312.11776-1-hdanton@sina.com> <20200825162329.11292-1-hdanton@sina.com> <5f46032e.1c69fb81.9880c.7a6cSMTPIN_ADDED_MISSING@mx.google.com> <20200827125747.5816-1-hdanton@sina.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-1.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2020-09-02 at 22:01 -0700, Cong Wang wrote: > Can you test the attached one-line fix? I think we are overthinking, > probably all > we need here is a busy wait. I think that will solve, but I also think that will kill NOLOCK performances due to really increased contention. At this point I fear we could consider reverting the NOLOCK stuff. I personally would hate doing so, but it looks like NOLOCK benefits are outweighed by its issues. Any other opinion more than welcome! Cheers, Paolo