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 882F5C636CD for ; Mon, 30 Jan 2023 13:35:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236560AbjA3Nfz (ORCPT ); Mon, 30 Jan 2023 08:35:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236504AbjA3Nfy (ORCPT ); Mon, 30 Jan 2023 08:35:54 -0500 Received: from mail-yb1-xb32.google.com (mail-yb1-xb32.google.com [IPv6:2607:f8b0:4864:20::b32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 523222C648 for ; Mon, 30 Jan 2023 05:35:53 -0800 (PST) Received: by mail-yb1-xb32.google.com with SMTP id 129so14048650ybb.0 for ; Mon, 30 Jan 2023 05:35:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=G7bHIsj5CD0I4ilihSfFwyjG5glNyA2Pq4/YoxuvE2c=; b=OwZzEt1aOjdubqNG50qkEWrRtN8qHjSzwqzwqxrcBg0nUzXjAGyP23CRc0NyjM+Zyd femf4k138UmtbIMf5F55VQbVLL4yW2SXzhH0wDlsu+8CLjAINQXlN0ZY/Ad6FtGWGHpr +NRWqUjv9QGE3EMdFYoSlkUKFqu9G3Wp0Sp11tF+GG4eomn1sR4V7J3r0jshrMsk7q0w cVrU3RE/y4Nweq4rkP26PB7463qLB5rp7dykqNJCTyf2eHt3eK15kMOBRsAwnDPQg6tt XZv9SyHg0fwxbAHlj1VfiskyHhqS2koyIShboxxmvjDWtCOEY7eWZO7JIV/AbkxDzwBb 9q7g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=G7bHIsj5CD0I4ilihSfFwyjG5glNyA2Pq4/YoxuvE2c=; b=DkCW2uQxAqlGAn1StIhEH8Ghq7QIPr6xVT19qpT+DpEAoSb1stN5Vr/JsM1ZqYC9Ua Lkn20SpaIVoR/1nD12Ntr+U0OIQS8WdJMn8p/ksCDaDwHX4SmcsjUPQ8TLwGFPuuB+Wf rmdEFNOSpXFrPCIxJBHeUS70+Cr9cnx6zhezebeeX0yr55x6+4TuVipuF6xfMYQ3iuOO n2q7CjuCbaaQNda2p+xUzXkks/iCgRdcFaqpEpvYr+ResmdPgo3Aeg9CCjniMNqBNEIn 1c2RI9XO4KQpiRnmi3UnofJDhng5KgFRgL6Xn9ufMjpBuLOwODAvpG3MHmSZxMF/iuiU T1Hw== X-Gm-Message-State: AFqh2krq9XW8twr30390+MAtgQ5Ltvmra738Cq7rRv3Hjq7C7tY6y6sR 59pF6cBujIYvF7aQcJrRZx3xLOZ8nXA3ZVnUK9vPCg== X-Google-Smtp-Source: AMrXdXv4IhoNoQyKPn5TvHWkprEWumyW0THrjKxQU5y+tSgAW3MfscEL+cJCYPDlQtUTOnc6y/ttYfP4jg98K7sLZJ0= X-Received: by 2002:a25:53c2:0:b0:703:e000:287 with SMTP id h185-20020a2553c2000000b00703e0000287mr5440320ybb.171.1675085752416; Mon, 30 Jan 2023 05:35:52 -0800 (PST) MIME-Version: 1.0 References: <20230127181625.286546-1-andrei.gherzan@canonical.com> In-Reply-To: From: Willem de Bruijn Date: Mon, 30 Jan 2023 08:35:16 -0500 Message-ID: Subject: Re: [PATCH] selftests: net: udpgso_bench_tx: Introduce exponential back-off retries To: Andrei Gherzan Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Shuah Khan , netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jan 30, 2023 at 7:51 AM Andrei Gherzan wrote: > > On 23/01/30 09:26AM, Paolo Abeni wrote: > > On Fri, 2023-01-27 at 17:03 -0500, Willem de Bruijn wrote: > > > On Fri, Jan 27, 2023 at 1:16 PM Andrei Gherzan > > > wrote: > > > > > > > > The tx and rx test programs are used in a couple of test scripts including > > > > "udpgro_bench.sh". Taking this as an example, when the rx/tx programs > > > > are invoked subsequently, there is a chance that the rx one is not ready to > > > > accept socket connections. This racing bug could fail the test with at > > > > least one of the following: > > > > > > > > ./udpgso_bench_tx: connect: Connection refused > > > > ./udpgso_bench_tx: sendmsg: Connection refused > > > > ./udpgso_bench_tx: write: Connection refused > > > > > > > > This change addresses this by adding routines that retry the socket > > > > operations with an exponential back off algorithm from 100ms to 2s. > > > > > > > > Fixes: 3a687bef148d ("selftests: udp gso benchmark") > > > > Signed-off-by: Andrei Gherzan > > > > > > Synchronizing the two processes is indeed tricky. > > > > > > Perhaps more robust is opening an initial TCP connection, with > > > SO_RCVTIMEO to bound the waiting time. That covers all tests in one > > > go. > > > > Another option would be waiting for the listener(tcp)/receiver(udp) > > socket to show up in 'ss' output before firing-up the client - quite > > alike what mptcp self-tests are doing. > > I like this idea. I have tested it and it works as expected with the > exeception of: > > ./udpgso_bench_tx: sendmsg: No buffer space available > > Any ideas on how to handle this? I could retry and that works. This happens (also) without the zerocopy flag, right? That It might mean reaching the sndbuf limit, which can be adjusted with SO_SNDBUF (or SO_SNDBUFFORCE if CAP_NET_ADMIN). Though I would not expect this test to bump up against that limit. A few zerocopy specific reasons are captured in https://www.kernel.org/doc/html/latest/networking/msg_zerocopy.html#transmission.