From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9BE01321B7 for ; Wed, 8 Nov 2023 18:08:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="R6BKhcW3" Received: from mail-ed1-x52c.google.com (mail-ed1-x52c.google.com [IPv6:2a00:1450:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE4BA1FEB for ; Wed, 8 Nov 2023 10:08:44 -0800 (PST) Received: by mail-ed1-x52c.google.com with SMTP id 4fb4d7f45d1cf-53de8fc1ad8so12144082a12.0 for ; Wed, 08 Nov 2023 10:08:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google09082023; t=1699466923; x=1700071723; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:from:to:cc:subject:date :message-id:reply-to; bh=OXRTWOMUNcJmkjQbAZY5Z0iXJWssUD8btwZJIgiRnSc=; b=R6BKhcW34p5Mw1PAE7JrntVO6hyJW6u7EXFvcN9sLfjf7NPq1W89EAz/pHr4ueU5WU aF+218byFAgjBlZpnC3xKG/C36W1hNh3mftmb+Su8WDgsGcoRed40vMRxsS48tY7nHcg sJZwgCAtx27f4BlGWUhWoPRFF8ukyh/Vz2jhvQg+J4JhJqhkv2Mr8QUyLi7NjA/hzakZ YQxQEhZnGcNo1qbom5VVfKfTjRjXQy93Z3RNM1osSbUAuvJD5QqXH0wo5rmsHkxczWvj pCVGshCqLQvwb01UgMKtaphBJqyQIT+hOrXq0L3+BQgzO7t/ntg/1sRNigFaxpZlTyMz MhVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699466923; x=1700071723; h=content-transfer-encoding:mime-version:message-id:in-reply-to:date :subject:cc:to:from:user-agent:references:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=OXRTWOMUNcJmkjQbAZY5Z0iXJWssUD8btwZJIgiRnSc=; b=r238pDHm2sF9ghsTFs5eDPoPtMK17TGjzuKVBEsZ3hy9Vxt+u7837hghXvmxlx9jPq B0acibCnGIHC1+QgTXOlVZQjsn8eZQUeBwZSqiG0x2yDfkfJTzF98mG5BLZaeZ4vfPmZ b6J4uunPklcd8u1TNfNCxBopT3b+nyVLuZVNW9Z7IU3koHW5sYdlfByb6mvYhRCDEM/u SCmg3QOR4tvXC7kyvLALDagmSO48lsSMl3irdbOE0sRzkLeRsUTeC3zslRtB6ztK4VU7 EInwUa99+nDqqyVI06NZe4NcBZnrVHwwBaZueYVUc8rD/Ka8rKOovjhiX0K5T33inETv zCCQ== X-Gm-Message-State: AOJu0YzBEdirklJzlRzNfBuLYrb1lUjMOBlv47pY52nUJMvjfrECi4MX Yr4DYiBUZqlN1YOqq4TOR+nrjg== X-Google-Smtp-Source: AGHT+IE8foAOmvHY8FYHpQiJycUqZ00jR++mzKvCgZjL3jB7F67NLcShlJmBGFYtw2Yc7EK+F9to1A== X-Received: by 2002:a17:907:26c4:b0:9be:45b3:1c3c with SMTP id bp4-20020a17090726c400b009be45b31c3cmr2135498ejc.64.1699466923181; Wed, 08 Nov 2023 10:08:43 -0800 (PST) Received: from cloudflare.com (79.184.209.104.ipv4.supernova.orange.pl. [79.184.209.104]) by smtp.gmail.com with ESMTPSA id oy7-20020a170907104700b009ad89697c86sm1416534ejb.144.2023.11.08.10.08.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Nov 2023 10:08:42 -0800 (PST) References: <87jzqsld6q.fsf@cloudflare.com> User-agent: mu4e 1.6.10; emacs 28.3 From: Jakub Sitnicki To: Willem de Bruijn Cc: Willem de Bruijn , netdev@vger.kernel.org, kernel-team@cloudflare.com Subject: Re: EIO on send with UDP_SEGMENT Date: Wed, 08 Nov 2023 18:55:49 +0100 In-reply-to: Message-ID: <87fs1gkthv.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Wed, Nov 08, 2023 at 10:10 AM -05, Willem de Bruijn wrote: > On Wed, Nov 8, 2023 at 6:03=E2=80=AFAM Jakub Sitnicki wrote: [...] >> Do you think the restriction in udp_send_skb can be lifted or tweaked? > > The argument against has been that segmentation offload offers no > performance benefit if the stack has to fall back onto software > checksumming. Interesting. Thanks for sharing the context. Must admit, it would have not been my first guess that the software GSO+checksum itself is not worth it. Despite it happening late on the TX path. > If this limitation makes userspace code more complex, by having to > branch between segmentation offload and not depending on device > features, that would be an argument to drop it. As you point out, it > is not needed for correctness. That answers my question. Thanks for feedback.