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 1AE7A1643F for ; Tue, 11 Jul 2023 07:10:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53BE2C433C8; Tue, 11 Jul 2023 07:09:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689059399; bh=J5dPFWayAHymGhGoWOwA1Md3KDXTm8NjXATd6bPe9fg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R2YvfoM1iQe8wwieuv9OH7O5hgtn596YmZtTZh9ShXMl3TuyNANTGa0w9EdNAuoWS mIx2uWZKdXpuTRmsNffN4UU9JWglxEJHo26wxr1l7Y9KeEDUs455En8U/6j0e2wdVr y//LvVj1veV5SASdwnzFnFjmWOrCkopGLDLZyyqngx0MoUQgTJ1YsUREkpifsxRO2F TyzJyB5Mv7tB9ld+g8h8PVa+nvWCsFJdzvEqykUlCKD39QBLqY00Mhg8qY5jefNYkj sxXjenPiU1guUPa81DZxL/2icEB9X9Hgr3LkWVcSxFHe06v2ApOHs6UW0RJjw4FLwA 9d/+uKl/s1XAg== Date: Tue, 11 Jul 2023 10:09:55 +0300 From: Leon Romanovsky To: Tony Nguyen Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, netdev@vger.kernel.org, Florian Kauer , kurt@linutronix.de, vinicius.gomes@intel.com, muhammad.husaini.zulkifli@intel.com, tee.min.tan@linux.intel.com, aravindhan.gunasekaran@intel.com, sasha.neftin@intel.com, Naama Meir Subject: Re: [PATCH net 4/6] igc: No strict mode in pure launchtime/CBS offload Message-ID: <20230711070955.GG41919@unreal> References: <20230710163503.2821068-1-anthony.l.nguyen@intel.com> <20230710163503.2821068-5-anthony.l.nguyen@intel.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=us-ascii Content-Disposition: inline In-Reply-To: <20230710163503.2821068-5-anthony.l.nguyen@intel.com> On Mon, Jul 10, 2023 at 09:35:01AM -0700, Tony Nguyen wrote: > From: Florian Kauer > > The flags IGC_TXQCTL_STRICT_CYCLE and IGC_TXQCTL_STRICT_END > prevent the packet transmission over slot and cycle boundaries. > This is important for taprio offload where the slots and > cycles correspond to the slots and cycles configured for the > network. > > However, the Qbv offload feature of the i225 is also used for > enabling TX launchtime / ETF offload. In that case, however, > the cycle has no meaning for the network and is only used > internally to adapt the base time register after a second has > passed. > > Enabling strict mode in this case would unnecessarily prevent > the transmission of certain packets (i.e. at the boundary of a > second) and thus interferes with the ETF qdisc that promises > transmission at a certain point in time. > > Similar to ETF, this also applies to CBS offload that also should > not be influenced by strict mode unless taprio offload would be > enabled at the same time. > > This fully reverts > commit d8f45be01dd9 ("igc: Use strict cycles for Qbv scheduling") > but its commit message only describes what was already implemented > before that commit. The difference to a plain revert of that commit > is that it now copes with the base_time = 0 case that was fixed with > commit e17090eb2494 ("igc: allow BaseTime 0 enrollment for Qbv") > > In particular, enabling strict mode leads to TX hang situations > under high traffic if taprio is applied WITHOUT taprio offload > but WITH ETF offload, e.g. as in > > sudo tc qdisc replace dev enp1s0 parent root handle 100 taprio \ > num_tc 1 \ > map 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 \ > queues 1@0 \ > base-time 0 \ > sched-entry S 01 300000 \ > flags 0x1 \ > txtime-delay 500000 \ > clockid CLOCK_TAI > sudo tc qdisc replace dev enp1s0 parent 100:1 etf \ > clockid CLOCK_TAI \ > delta 500000 \ > offload \ > skip_sock_check > > and traffic generator > > sudo trafgen -i traffic.cfg -o enp1s0 --cpp -n0 -q -t1400ns > > with traffic.cfg > > #define ETH_P_IP 0x0800 > > { > /* Ethernet Header */ > 0x30, 0x1f, 0x9a, 0xd0, 0xf0, 0x0e, # MAC Dest - adapt as needed > 0x24, 0x5e, 0xbe, 0x57, 0x2e, 0x36, # MAC Src - adapt as needed > const16(ETH_P_IP), > > /* IPv4 Header */ > 0b01000101, 0, # IPv4 version, IHL, TOS > const16(1028), # IPv4 total length (UDP length + 20 bytes (IP header)) > const16(2), # IPv4 ident > 0b01000000, 0, # IPv4 flags, fragmentation off > 64, # IPv4 TTL > 17, # Protocol UDP > csumip(14, 33), # IPv4 checksum > > /* UDP Header */ > 10, 0, 48, 1, # IP Src - adapt as needed > 10, 0, 48, 10, # IP Dest - adapt as needed > const16(5555), # UDP Src Port > const16(6666), # UDP Dest Port > const16(1008), # UDP length (UDP header 8 bytes + payload length) > csumudp(14, 34), # UDP checksum > > /* Payload */ > fill('W', 1000), > } > > and the observed message with that is for example > > igc 0000:01:00.0 enp1s0: Detected Tx Unit Hang > Tx Queue <0> > TDH > TDT > next_to_use > next_to_clean > buffer_info[next_to_clean] > time_stamp > next_to_watch <00000000245a4efb> > jiffies > desc.status <1048000> > > Fixes: d8f45be01dd9 ("igc: Use strict cycles for Qbv scheduling") > Signed-off-by: Florian Kauer > Reviewed-by: Kurt Kanzenbach > Tested-by: Naama Meir > Signed-off-by: Tony Nguyen > --- > drivers/net/ethernet/intel/igc/igc_tsn.c | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > Thanks, Reviewed-by: Leon Romanovsky