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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8D41C46467 for ; Sat, 7 Jan 2023 18:50:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230240AbjAGSuK (ORCPT ); Sat, 7 Jan 2023 13:50:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232918AbjAGStv (ORCPT ); Sat, 7 Jan 2023 13:49:51 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60CBFBF4B for ; Sat, 7 Jan 2023 10:49:03 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1673117342; 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: in-reply-to:in-reply-to:references:references; bh=6HHLzKWF7oTmdlJ4N4NLyzD0Y4y9Cs9ns8nguRyOKzc=; b=HUPSn7pdI0gmroob9fwmwlqX0FUlCHe+U0KvilDJysEmNcJSS2Q7rRU4XbwFfb5/J/kKyv bwX3Ii7uzL7gkQzEjCAgH8Ddl0YP79NzaLPebXPy9HHetz2nSfz5CCS0GwSD9ea2hF8SUq 6OHS5rV0cK92EQzS3jJ+Fb0/ZBbJ4tY= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-144-6D5Pl86XPPq3zbz_WcfA-A-1; Sat, 07 Jan 2023 13:49:00 -0500 X-MC-Unique: 6D5Pl86XPPq3zbz_WcfA-A-1 Received: by mail-ed1-f72.google.com with SMTP id y21-20020a056402359500b0048123f0f8deso3127707edc.23 for ; Sat, 07 Jan 2023 10:49:00 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=6HHLzKWF7oTmdlJ4N4NLyzD0Y4y9Cs9ns8nguRyOKzc=; b=IcSagu+lUCm19Q8tWueFA7Gdn9FEE//9fcJWHK4XEJARkyRdrtzktuhXpWAvujpTRE MywQci3VYZs1P1YShrz4biz5HP8WBEh/UwsQEAM6SHuKWHT/0GynGi6IDdg8JHy3ZkOq XC1WxE86Jh57Q5ad7EoJoewrLsWDVnFnMN75CoTR4E+I1BkPb63/R8XqY34p1PoTCibV sPjQkEgUZVj93qb21RuNIZ3fY7lMJOpRMqCTatbKX0GeK+fNUFWmfjdFGDZEhplqcQAV 9ex2gATCOUsLG3YSkCG+YGSSK/X1L60HW49QIAhe4YHr17BPy7yxARIjiFKgc563Ti7s MbMw== X-Gm-Message-State: AFqh2krO8pCed7U7eqHV54AlrSVkY5K6Wsj3VZwOLUB9lly7Z/+cJA2n Mh2TDQwCbHtj0s+7THc3+gOD+pPGvCjKwuCkRDWF3N2cy8gWwymYFaYGVUwpdOC6QlAm5vjTSjI 9DfEwgiSqD0SwiIv5MSlDqKA= X-Received: by 2002:aa7:dd45:0:b0:494:fae3:c0df with SMTP id o5-20020aa7dd45000000b00494fae3c0dfmr6489802edw.12.1673117338776; Sat, 07 Jan 2023 10:48:58 -0800 (PST) X-Google-Smtp-Source: AMrXdXtvDLfR2b190OpE9raCZu23jMNIgCNQGvQm1b5E8FgE9APKcSw9ji57ZieFJt3a7yxLKcbpCg== X-Received: by 2002:aa7:dd45:0:b0:494:fae3:c0df with SMTP id o5-20020aa7dd45000000b00494fae3c0dfmr6489779edw.12.1673117338026; Sat, 07 Jan 2023 10:48:58 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id u9-20020aa7d889000000b00457b5ba968csm1750401edq.27.2023.01.07.10.48.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Jan 2023 10:48:57 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id F40238DA324; Sat, 7 Jan 2023 19:48:56 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Dave Taht , team lnx Cc: xdp-newbies@vger.kernel.org Subject: Re: Pause and unpause queue In-Reply-To: References: <87sfgnzukv.fsf@toke.dk> X-Clacks-Overhead: GNU Terry Pratchett Date: Sat, 07 Jan 2023 19:48:56 +0100 Message-ID: <87cz7qyycn.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: xdp-newbies@vger.kernel.org Dave Taht writes: > On Sat, Jan 7, 2023 at 10:08 AM team lnx wrote: >> >> sure, during xdp redirect i found that sometimes the number of packets >> arrived are too many for an interface > > That is often the case. > >> to handle in which case. Hence thought to experiment with tx pause to >> make room for successive packets and then unpause ! > > "pauses" are really not how the internet works, there needs to be end > to end signalling to "slow down", either via packet loss, or marking. > RFC970 is a good read here. Actually it is, kinda, at this level: Pausing the TX interface (when the HWQ is full) is how the regular network stack creates backpressure against the qdisc, which is what allows fq_codel and friends to function. This is missing entirely from the XDP redirect path, which is what we're trying to fix... -Toke