From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 198242D4806; Wed, 11 Feb 2026 01:56:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770775000; cv=none; b=tqldzTXXYgW98brfJ+HYdc2nvzzviNqhYzWIVVL8O10OOz2SkQK0DeoqyxyK4ATGZjw9bv9gLjFCPyOZho3OeHglJUalKEMfFV4G5rgbDtSxb97Fuh/0ozOFhPqpCvID23wk0KSj7b4eWib81ulYxRfxxuf2F0nOo+wmdumc+QI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770775000; c=relaxed/simple; bh=BMY9+yKdeAiBkeAYgMFch3HHKhcWuWYgHyr8mhgMM1k=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=hu/Xp8XsxKq+8U7B4xMdPJ1PN0APtcPMPrNtjnKA9cB2iN1/tKcknwVKPsTPjDGgbZ1zJJ3zApPdmvKoYBOLYFYorsAz1o349yOfBcmo+PWtNShc+j8OyhHwWSmyDdaqxXk1MvnSmI238KxEivoIPwagGVEQIYGqVSFNcoHpl/A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NN1v05Kh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NN1v05Kh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3947C116C6; Wed, 11 Feb 2026 01:56:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770774999; bh=BMY9+yKdeAiBkeAYgMFch3HHKhcWuWYgHyr8mhgMM1k=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NN1v05KhlBhfgpDMAO4i6qxV4EfwOA80jEm81MpnglwxPREGtJNB0Lq5Z3ETCSbrC AI9Io/w5UYMNE4GZm6FHIvLFv7MlvOpzLRksEHgp2JrF7OGcKaGotwr0qNMT40dCzu I2uEQElwTfLNCQIf7uY57zlN3aVdjD4u1HsUCSDC2mWlThh6YQ9QvcP0PE/KELYNxu zsHUM1N3qgoWE6zc6mbak+MkDdcbd8GePhWYgkxx+ZnW9hlAbJZoBdfCHuaQEGMJmR u96gJCrNpvW5EjjVV3Ih2r/p99hgdVKjHh4aKGo79CTr+wOVuZlCV/ULP+sI0EBxfA PKldZe73yRz3w== Date: Tue, 10 Feb 2026 17:56:38 -0800 From: Jakub Kicinski To: Willem de Bruijn Cc: davem@davemloft.net, netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, shuah@kernel.org, willemb@google.com, petrm@nvidia.com, donald.hunter@gmail.com, michael.chan@broadcom.com, pavan.chebbi@broadcom.com, linux-kselftest@vger.kernel.org Subject: Re: [PATCH net-next v2 6/9] selftests: drv-net: gro: use SO_TXTIME to schedule packets together Message-ID: <20260210175638.123782b2@kernel.org> In-Reply-To: References: <20260207003509.3927744-1-kuba@kernel.org> <20260207003509.3927744-7-kuba@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 08 Feb 2026 21:39:38 -0500 Willem de Bruijn wrote: > Jakub Kicinski wrote: > > Longer packet sequence tests are quite flaky when the test is run > > over a real network. Try to avoid at least the jitter on the sender > > side by scheduling all the packets to be sent at once using SO_TXTIME. > > Use hardcoded tx time of 5msec in the future. In my test increasing > > this time past 2msec makes no difference so 5msec is plenty of margin. > > Since we now expect more output buffering make sure to raise SNDBUF. > > > > Experimenting with long sequences I see frequent failures when sending > > 200 packets, only 50-100 packets get coalesced. With this change > > up to 1000 packets get coalesced relatively reliably. > > > > Reviewed-by: Petr Machata > > Signed-off-by: Jakub Kicinski > > Does this require having FQ installed? I don't see any qdisc config > in the GRO test. It's a bit of an opportunistic optimization. I initially intended it for for the "long sequence of packets" test. But I failed to get AF_PACKET+FQ to cooperate sufficiently to queue all of the packets in the same bucket. Otherwise FQ "sorts" the packets, and breaks what the test is trying to do :( Oh, and as mentioned in the commit msg - this improvement is intended for HW-GRO, which may have very low timeouts. The test already configures timeout for SW GRO to a very high value, so don't think we would gain anything from setting up FQ on veth/netdevsim for the SW test. So IDK what to do with this patch. Maybe I should just drop it? It _seemed_ useful, but I don't have enough datapoints to do a real comparison of how much it improves reliability.