Re: [PATCH] igb: add module param to set max-rss-queues.

On 03/24/2017 04:14 PM, Stephen Hemminger wrote:

On Fri, 24 Mar 2017 14:20:56 -0700
Ben Greear [off-list ref] wrote:

quoted

On 03/24/2017 02:12 PM, David Miller wrote:

quoted

From: greearb@candelatech.com
Date: Fri, 24 Mar 2017 13:58:47 -0700

quoted

From: Ben Greear <redacted>

In systems where you may have a very large number of network
adapters, certain drivers may consume an unfair amount of
IRQ resources.  So, allow a module param that will limit the
number of IRQs at driver load time.  This way, other drivers
(40G Ethernet, for instance), which probably will need the
multiple IRQs more, will not be starved of IRQ resources.

Signed-off-by: Ben Greear <redacted>

Sorry, no module params.

Use generic run-time facilities such as ethtool to configure
such things.

You cannot call ethtool before module load time, and that is when
the IRQs are first acquired.  It may be way more useful to give each
of 20 network adapters 2 irqs than have the first few grab 16 and the rest
get lumped into legacy crap.

Almost all network devices do not acquire interrupts until device is brought up.
I.e request_irq is called from open not probe. This is done so that configuration
can be done and also so that unused ports don't consume interrupt space.

If I ever have to deal with this on stock kernels again I'll keep that in mind.

Thanks,
Ben

-- 
Ben Greear [off-list ref]
Candela Technologies Inc  http://www.candelatech.com