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Date: Fri, 5 Jan 2024 19:21:48 +0100
From: Petr =?UTF-8?B?VGVzYcWZw61r?= <petr@tesarici.cz>
To: Andrew Lunn <andrew@lunn.ch>
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Subject: Re: [PATCH] net: stmmac: protect statistics updates with a spinlock
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On Fri, 5 Jan 2024 18:36:45 +0100
Andrew Lunn <andrew@lunn.ch> wrote:

> > This only leaves an atomic_t in hard irq context. I have tried to find
> > something that could relax the requirement, but AFAICS at least some
> > setups use several interrupts that can be delivered to different CPUs
> > simultaneously, and all of them will walk over all channels. So we're
> > left with an atomic_t here.  
> 
> You might want to consider per CPU statistics. Since each CPU has its
> own structure of statistics, you don't need atomic.
> 
> The code actually using the statistics then needs to sum up the per
> CPU statistics, and using syncp should be sufficient for that.

Thanks for the tip.

Honestly, the more I'm looking into this, the less I am convinced that
it is worth the effort, but yeah, if we touch this code now, let's do
things properly. ;-)

> Maybe look at mvneta.c for inspiration.

I think I know what you mean, but I'll have a look.

Petr T