linux-kernel - Re: [PATCH iwl-next v4 9/9] igc: Add support to get frame preemption statistics via ethtool

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Message-ID: <20250212215408.v47eb42zx67ij6vp@skbuf>
Date: Wed, 12 Feb 2025 23:54:08 +0200
From: Vladimir Oltean <vladimir.oltean@....com>
To: Faizal Rahim <faizal.abdul.rahim@...ux.intel.com>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
	Przemek Kitszel <przemyslaw.kitszel@...el.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S . Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Simon Horman <horms@...nel.org>,
	Russell King <linux@...linux.org.uk>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Jesper Dangaard Brouer <hawk@...nel.org>,
	John Fastabend <john.fastabend@...il.com>,
	Furong Xu <0x1207@...il.com>,
	Russell King <rmk+kernel@...linux.org.uk>,
	Serge Semin <fancer.lancer@...il.com>,
	Xiaolei Wang <xiaolei.wang@...driver.com>,
	Suraj Jaiswal <quic_jsuraj@...cinc.com>,
	Kory Maincent <kory.maincent@...tlin.com>,
	Gal Pressman <gal@...dia.com>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	Andrew Halaney <ahalaney@...hat.com>,
	Choong Yong Liang <yong.liang.choong@...ux.intel.com>,
	Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>,
	Vinicius Costa Gomes <vinicius.gomes@...el.com>,
	intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-stm32@...md-mailman.stormreply.com,
	linux-arm-kernel@...ts.infradead.org, bpf@...r.kernel.org
Subject: Re: [PATCH iwl-next v4 9/9] igc: Add support to get frame preemption
 statistics via ethtool

On Mon, Feb 10, 2025 at 02:02:07AM -0500, Faizal Rahim wrote:
> Implemented "ethtool --include-statistics --show-mm" callback for IGC.
> 
> Tested preemption scenario to check preemption statistics:
> 1) Trigger verification handshake on both boards:
>     $ sudo ethtool --set-mm enp1s0 pmac-enabled on
>     $ sudo ethtool --set-mm enp1s0 tx-enabled on
>     $ sudo ethtool --set-mm enp1s0 verify-enabled on

For the record, all these can be enabled at the same time through a
single ethtool command.

> 2) Set preemptible or express queue in taprio for tx board:
>     $ sudo tc qdisc replace dev enp1s0 parent root handle 100 taprio \
>       num_tc 4 map 3 2 1 0 3 3 3 3 3 3 3 3 3 3 3 3 \
>       queues 1@0 1@1 1@2 1@3 base-time 0 sched-entry S F 100000 \
>       fp E E P P
> 3) Send large size packets on preemptible queue
> 4) Send small size packets on express queue to preempt packets in
>    preemptible queue
> 5) Show preemption statistics on the receiving board:
>    $ ethtool --include-statistics --show-mm enp1s0
>      MAC Merge layer state for enp1s0:
>      pMAC enabled: on
>      TX enabled: on
>      TX active: on
>      TX minimum fragment size: 64
>      RX minimum fragment size: 60
>      Verify enabled: on
>      Verify time: 128
>      Max verify time: 128
>      Verification status: SUCCEEDED
>      Statistics:
>      	MACMergeFrameAssErrorCount: 0
> 	MACMergeFrameSmdErrorCount: 0
> 	MACMergeFrameAssOkCount: 511
> 	MACMergeFragCountRx: 764
> 	MACMergeFragCountTx: 0
> 	MACMergeHoldCount: 0

nitpick: mix of tabs and spaces.

> diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
> index f15ac7565fbd..cd5160315993 100644
> --- a/drivers/net/ethernet/intel/igc/igc_main.c
> +++ b/drivers/net/ethernet/intel/igc/igc_main.c
> @@ -3076,6 +3076,7 @@ static bool igc_clean_tx_irq(struct igc_q_vector *q_vector, int napi_budget)
>  			break;
>  
>  		if (static_branch_unlikely(&igc_fpe_enabled) &&
> +		    adapter->fpe.mmsv.pmac_enabled &&

This bit is misplaced in this patch.
Also, both conditions, being repeated twice as they are, could be placed
in an igc_pmac_enabled() helper function or similar.

>  		    igc_fpe_transmitted_smd_v(tx_desc))
>  			ethtool_mmsv_event_handle(&adapter->fpe.mmsv,
>  						  ETHTOOL_MMSV_LD_SENT_VERIFY_MPACKET);