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From: Andrew Lunn <andrew@lunn.ch>
To: Gerhard Engleder <gerhard@engleder-embedded.com>
Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org,
	edumazet@google.com, pabeni@redhat.com
Subject: Re: [PATCH net-next 1/4] tsnep: Throttle interrupts
Date: Thu, 17 Nov 2022 21:33:56 +0100	[thread overview]
Message-ID: <Y3aatP+384keCkpN@lunn.ch> (raw)
In-Reply-To: <20221117201440.21183-2-gerhard@engleder-embedded.com>

On Thu, Nov 17, 2022 at 09:14:37PM +0100, Gerhard Engleder wrote:
> Without interrupt throttling, iperf server mode generates a CPU load of
> 100% (A53 1.2GHz). Also the throughput suffers with less than 900Mbit/s
> on a 1Gbit/s link. The reason is a high interrupt load with interrupts
> every ~20us.

Not my area of expertise, but is NAPI working correctly? It should be
that you disable interrupts while NAPI is polling, and only re-enable
interrupts when polling has stopped. If you are receiving at near line
rate at 100% load, i would of thought that NAPI would be polling most
of the time and interrupts would be mostly disabled?

Interrupt coalescence makes a lot of sense thought, so the patch
itself is useful.

       Andrew

  reply	other threads:[~2022-11-17 20:34 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-17 20:14 [PATCH net-next 0/4] tsnep: Throttle irq, rotten pkts, RX buffer alloc and ethtool_get_channels() Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 1/4] tsnep: Throttle interrupts Gerhard Engleder
2022-11-17 20:33   ` Andrew Lunn [this message]
2022-11-18  5:50     ` Gerhard Engleder
2022-11-19  1:24   ` Jakub Kicinski
2022-11-19 20:46     ` Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 2/4] tsnep: Fix rotten packets Gerhard Engleder
2022-11-17 20:39   ` Andrew Lunn
2022-11-18  6:13     ` Gerhard Engleder
2022-11-19  1:26   ` Jakub Kicinski
2022-11-19 20:47     ` Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 3/4] tsnep: Add ethtool get_channels support Gerhard Engleder
2022-11-17 20:14 ` [PATCH net-next 4/4] tsnep: Rework RX buffer allocation Gerhard Engleder

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