netdev - RE: [Intel-wired-lan] [PATCH iwl-next v2 4/4] igb: Get rid of spurious interrupts

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Message-ID: <MN0PR11MB62320119BB9C1447B1DA46B29CD52@MN0PR11MB6232.namprd11.prod.outlook.com>
Date: Fri, 7 Mar 2025 10:26:43 +0000
From: "Kumari, Sweta" <sweta.kumari@...el.com>
To: Kurt Kanzenbach <kurt@...utronix.de>, "Nguyen, Anthony L"
	<anthony.l.nguyen@...el.com>, "Kitszel, Przemyslaw"
	<przemyslaw.kitszel@...el.com>
CC: 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>, Sebastian Andrzej Siewior
	<bigeasy@...utronix.de>, "Damato, Joe" <jdamato@...tly.com>, Gerhard Engleder
	<gerhard@...leder-embedded.com>, "intel-wired-lan@...ts.osuosl.org"
	<intel-wired-lan@...ts.osuosl.org>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH iwl-next v2 4/4] igb: Get rid of
 spurious interrupts



> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@...osl.org> On Behalf Of
> Kurt Kanzenbach
> Sent: Monday, February 17, 2025 5:01 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@...el.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@...el.com>
> Cc: 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>; Sebastian
> Andrzej Siewior <bigeasy@...utronix.de>; Damato, Joe
> <jdamato@...tly.com>; Gerhard Engleder <gerhard@...leder-
> embedded.com>; intel-wired-lan@...ts.osuosl.org; netdev@...r.kernel.org;
> Kurt Kanzenbach <kurt@...utronix.de>
> Subject: [Intel-wired-lan] [PATCH iwl-next v2 4/4] igb: Get rid of spurious
> interrupts
> 
> When running the igc with XDP/ZC in busy polling mode with deferral of hard
> interrupts, interrupts still happen from time to time. That is caused by the igb
> task watchdog which triggers Rx interrupts periodically.
> 
> That mechanism has been introduced to overcome skb/memory allocation
> failures [1]. So the Rx clean functions stop processing the Rx ring in case of
> such failure. The task watchdog triggers Rx interrupts periodically in the hope
> that memory became available in the mean time.
> 
> The current behavior is undesirable for real time applications, because the
> driver induced Rx interrupts trigger also the softirq processing. However, all
> real time packets should be processed by the application which uses the busy
> polling method.
> 
> Therefore, only trigger the Rx interrupts in case of real allocation failures.
> Introduce a new flag for signaling that condition.
> 
> Follow the same logic as in commit 8dcf2c212078 ("igc: Get rid of spurious
> interrupts").
> 
> [1] -
> https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=3b
> e507547e6177e5c808544bd6a2efa2c7f1d436
> 
> Reviewed-by: Joe Damato <jdamato@...tly.com>
> Signed-off-by: Kurt Kanzenbach <kurt@...utronix.de>
> ---
>  drivers/net/ethernet/intel/igb/igb.h      |  3 ++-
>  drivers/net/ethernet/intel/igb/igb_main.c | 29
> +++++++++++++++++++++++++----  drivers/net/ethernet/intel/igb/igb_xsk.c  |
> 1 +
>  3 files changed, 28 insertions(+), 5 deletions(-)
> 
Tested-by: Sweta Kumari <sweta.kumari@...el.com>