netdev - Re: [PATCH net-next 4/4] ionic: separate interrupt for Tx and Rx

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Message-ID: <20200724175611.7b514bb1@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 24 Jul 2020 17:56:11 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Shannon Nelson <snelson@...sando.io>
Cc:     netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH net-next 4/4] ionic: separate interrupt for Tx and Rx

On Fri, 24 Jul 2020 17:23:26 -0700 Shannon Nelson wrote:
> Add the capability to split the Tx queues onto their own
> interrupts with their own napi contexts.  This gives the
> opportunity for more direct control of Tx interrupt
> handling, such as CPU affinity and interrupt coalescing,
> useful for some traffic loads.
> 
> To enable, use the ethtool private flag:
> 	ethtool --set-priv-flag enp20s0 split-q-intr on
> To restore defaults
> 	ethtool --set-priv-flag enp20s0 split-q-intr off
> 
> When enabled, the number of queues is cut in half in order
> to reuse the interrupts that have already been allocated to
> the device.  When disabled, the queue count is restored.
> 
> Signed-off-by: Shannon Nelson <snelson@...sando.io>

Splitting queues into tx-only and rx-only is done like this:

ethtool -L enp20s0 rx N tx N combined 0

And then back to combined:

ethtool -L enp20s0 rx 0 tx 0 combined N

No need for a private flag here.