From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 58C3B448BBB; Tue, 11 Aug 2026 14:26:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786458413; cv=none; b=QL6EsG4FDY6GBYa8Wc5TJBSU+UGB/RBbg21lCw5tiBifsnYzOxLRB/+f4HTEk7Kx82zPCRsoYX1REG4vP6+ds+hwNahv5FtmojfVsKIdsydezm5vsXqIoYvt/UIClu4X6y69IlxnXQAM2hrPmYYXcihPfCCm/IlEi130IKccoN0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786458413; c=relaxed/simple; bh=Ue8zue8fhHadLkzART9NdhJHTb1WxMohxR7tgvjXXS8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uM/pMZucOud9Va6H5hWMMW6U6yt/dmsJvK7tbs5vz0MWxIN10Dnlv9Um0Y9O6lXXpO++t9EVSHtHjuUWBXKnRTKglmG3GVV30935HcMcEDoy2w059xsoDdZITmpjYJuPrx89qEjuCFxUuVNCDqHBWjhCb+YzTY8UBItd27VjAxU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EN8nWxDw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EN8nWxDw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 791CD1F000E9; Tue, 11 Aug 2026 14:26:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786458408; bh=Jkaoy25yfeQmT1UwUUgywiq4xtGMPE2KHeNj2B4MqLQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=EN8nWxDwwq+3wP/wh8yscDbKWKUAMT+Zm5oyCRSqNlgTDwSzuQrIhVNIN2VVvsVMJ CAD1gY8ilgPze7S/NPztJO7JYV5VPRQh/Tnd8pv/I/TLVoPPfTYMLzeA6yaw4qxfKt fV8vCGQ0308ojkWpxAlc57KpXrqM4j7y1SgufUpD7rPig5WDfKgqErNoQz3ldVKrxv qUXKnK1PUTQ01bSRdgCg68lFEcz/iJFitIcXBNBILyvIC4WwqAhcQ2FdVHuOAW3p1F HqI00fwSHOh7/CErHWBgLiHVUwkjVqU1su49QwzO6dS3d37Aacs2DnpKzcbJVmOzVr HBQo0sHwdep9A== Message-ID: Date: Tue, 11 Aug 2026 08:26:47 -0600 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 2/2] selftests: drv-net: let ethtool stats settle before reading Content-Language: en-US To: Jakub Kicinski , davem@davemloft.net Cc: netdev@vger.kernel.org, edumazet@google.com, pabeni@redhat.com, andrew+netdev@lunn.ch, horms@kernel.org, andrew@lunn.ch, shuah@kernel.org, idosch@nvidia.com, ioana.ciornei@nxp.com, petrm@nvidia.com, linux-kselftest@vger.kernel.org References: <20260808163653.2460381-1-kuba@kernel.org> <20260808163653.2460381-2-kuba@kernel.org> From: David Ahern In-Reply-To: <20260808163653.2460381-2-kuba@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/8/26 10:36 AM, Jakub Kicinski wrote: > Some devices refresh the statistics exposed via ethtool only > periodically, every stats-block-usecs (as reported by ethtool -c). > ethtool_std_stats and ethtool_rmon sample the counters immediately > after generating traffic, so on such devices they can read stale > values and fail with a delta short of the packets just sent. > > Add a hw_stats_settle() helper which sleeps for 1.25x the configured > stats-block-usecs (defaulting to 20ms when the device reports no, or > a zero, period). Use it for ethtool std stats and RMON. > The 1.25x/20msec heuristic matches what the Python tests do. > > Signed-off-by: Jakub Kicinski > --- > CC: andrew@lunn.ch > CC: shuah@kernel.org > CC: dsahern@kernel.org > CC: idosch@nvidia.com > CC: ioana.ciornei@nxp.com > CC: petrm@nvidia.com > CC: linux-kselftest@vger.kernel.org > --- > .../selftests/drivers/net/hw/ethtool_rmon.sh | 2 ++ > .../selftests/drivers/net/hw/ethtool_std_stats.sh | 2 ++ > tools/testing/selftests/net/forwarding/lib.sh | 15 +++++++++++++++ > 3 files changed, 19 insertions(+) > Reviewed-by: David Ahern