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 BF18313DDAE for ; Thu, 30 Apr 2026 12:31:08 +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=1777552268; cv=none; b=cEi1MMuKTVFTaiFv/mpGOiQsZngyLRJfdBk1xN/RkcwXRkgrEW4EMK5O0v0kxRRFKczkjo8YxJjOUiC5NB+e4YFFNznYq9NXRcu+Uih/dwrOYebCYYHHDkqMjUy1j+iXh/9kcKczRS7XmUlecaAdfJT7ptSPJ9UBZc36w67ErMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777552268; c=relaxed/simple; bh=Fp6nDvrdJ0an0Bdrc/rA4+2C/js0byI0WoX7NJWs4vA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SPqApafgJBdPDJEw3Ia25rIlgUzEbNV+hs7MNPcXAm4jal105TfYcAfNpClKRlFi87wEE5cPk3SwwfDipp4MR2PbhnYd9JHcVYVrm0tmK0tRQmZIHvppq9OxKPc7wVEKj1jgZtkv8chAMksD0TlASFDcihhJyZBX3TP7vmooBIs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=pgLyMkTi; 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="pgLyMkTi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F14BC2BCB3; Thu, 30 Apr 2026 12:31:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777552268; bh=Fp6nDvrdJ0an0Bdrc/rA4+2C/js0byI0WoX7NJWs4vA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pgLyMkTiyi8SFM/bzhidlofi3hmOnpPZ3WgG6HpkNTBPvXBHcHxTy+xC5M9K7GCl4 C/Ak/Cwh885KmWBQoE8irULblICMT0ZhE1BV7RIH4yc6X4mihwtjms5GUG6oz+H49d tOd30USNmI+S5VL06FfucLQxsBofO0UTl2t6zZxNy/xdne0CVusfq0+GSWuSmEB11i Bsqt5Mf1YbrX05D883ueN7q8gEoQSBjV7bnEv7Aeev1OpUSiz1be7LGkjWWvNG7E9R 4B+0E3g+TjCDWitUoCjwlPqKvrBAP00KYsDBgGWPq0SPM8+dO/NkNhgwl3pjgBHN3m CFIUu9smaMfcQ== Message-ID: Date: Thu, 30 Apr 2026 14:31:03 +0200 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 5/5] selftests: net: add veth BQL stress test To: Simon Schippers , =?UTF-8?Q?Jonas_K=C3=B6ppeler?= Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, horms@kernel.org, jhs@mojatatu.com, jiri@resnulli.us, kernel-team@cloudflare.com, kuba@kernel.org, netdev@vger.kernel.org, pabeni@redhat.com References: <20260324174719.1224337-7-hawk@kernel.org> <02a713ac-f794-416f-9d69-95ea98d515b6@tu-dortmund.de> <1c435d90-8d08-4ac1-8b84-cc72c0b4e30f@tu-berlin.de> <7bc8edc9-1b46-471a-9a6e-cd2c27aebcfc@tu-dortmund.de> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <7bc8edc9-1b46-471a-9a6e-cd2c27aebcfc@tu-dortmund.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 30/04/2026 11.45, Simon Schippers wrote: > On 4/30/26 11:17, Jonas Köppeler wrote: >> On 3/28/26 4:19 PM, Simon Schippers wrote: >>> Hi, thanks for your work! I am really interested in this patchset. >>> >>> I am planning to submit a similar patch set (see [1]) for the tun/tap >>> driver, where I am currently implementing qdisc backpressure similar >>> to that used in veth. >>> >>> Can you run pktgen [2] to see if there is a regression? >>> I think that there might be a slowdown due to BQL not choosing a big >>> enough queue size. >> I ran some tests using pktgen by replacing the trafficgen from the >> selftest with samples/pktgen/pktgen_sample01_simple.sh (Patch v3) >> and used --nrules 0. In general the throughput is quite similar: >> >> BQL disabled (using --bql-disable): >> 2378694pps 1141Mb/sec (1141773120bps) errors: 0 >> 2400898pps 1152Mb/sec (1152431040bps) errors: 0 >> 2358125pps 1131Mb/sec (1131900000bps) errors: 0 >> 2402034pps 1152Mb/sec (1152976320bps) errors: 0 >> 2362061pps 1133Mb/sec (1133789280bps) errors: 0 >> 2416301pps 1159Mb/sec (1159824480bps) errors: 0 >> 2398496pps 1151Mb/sec (1151278080bps) errors: 0 >> 2415200pps 1159Mb/sec (1159296000bps) errors: 0 >> 2375921pps 1140Mb/sec (1140442080bps) errors: 0 >> 2427419pps 1165Mb/sec (1165161120bps) errors: 0 >> 2382461pps 1143Mb/sec (1143581280bps) errors: 0 >> >> mean: 2392510pps >> >> BQL enabled: >> 2159545pps 1036Mb/sec (1036581600bps) errors: 0 >> 2321899pps 1114Mb/sec (1114511520bps) errors: 0 >> 2477853pps 1189Mb/sec (1189369440bps) errors: 0 >> 2447857pps 1174Mb/sec (1174971360bps) errors: 0 >> 2400284pps 1152Mb/sec (1152136320bps) errors: 0 >> 2442841pps 1172Mb/sec (1172563680bps) errors: 0 >> 2442540pps 1172Mb/sec (1172419200bps) errors: 0 >> 2410585pps 1157Mb/sec (1157080800bps) errors: 0 >> 2395902pps 1150Mb/sec (1150032960bps) errors: 0 >> 2393260pps 1148Mb/sec (1148764800bps) errors: 0 >> 2401959pps 1152Mb/sec (1152940320bps) errors: 0 >> >> mean: 2390411pps >> >> BQL enabled is ~2099pps (~0.09%) lower than BQL disabled. > > Sounds great! > > One more thing: > Could you check what BQL limit settles during the test run using > something like: > > watch -n 0.1 'cat /sys/class/net/XXXXX/queues/tx-0/byte_queue_limits/limit' FYI: The selftest already tracks BQL "limit" and "inflight". - Jonas can just report those BQL inflight logs +print_periodic_stats() { + local elapsed="$1" + + # BQL stats and watchdog counter + WD_CNT=$(cat /sys/class/net/${VETH_A}/queues/tx-0/tx_timeout \ + 2>/dev/null) || WD_CNT="?" + if [ -n "$BQL_DIR" ] && [ -d "$BQL_DIR" ]; then + INFLIGHT=$(cat "$BQL_DIR/inflight" 2>/dev/null || echo "?") + LIMIT=$(cat "$BQL_DIR/limit" 2>/dev/null || echo "?") + echo " [${elapsed}s] BQL inflight=${INFLIGHT} limit=${LIMIT}" \ + "watchdog=${WD_CNT}" + else + echo " [${elapsed}s] watchdog=${WD_CNT} (no BQL sysfs)" + fi > I guess it will just choose the ptr_ring size as limit in this case, > but it would be nice if you could briefly verify this :) > > Thanks! > >> >>> Thanks! >>> >>> [1] Link:https://lore.kernel.org/all/20260312130639.138988-1-simon.schippers@tu-dortmund.de/ >>> [2] Link:https://www.kernel.org/doc/html/latest/networking/pktgen.html