Re: [PATCH 1/4] softirq: implement IRQ flood detection mechanism

From: Thomas Gleixner
Date: Tue Aug 27 2019 - 19:12:31 EST

On Wed, 28 Aug 2019, Ming Lei wrote:
> On Tue, Aug 27, 2019 at 06:19:00PM +0200, Thomas Gleixner wrote:
> > > We definitely are not going to have a 64bit multiplication and division on
> > > every interrupt. Asided of that this breaks 32bit builds all over the place.
> >
> > That said, we already have infrastructure for something like this in the
> > core interrupt code which is optimized to be lightweight in the fast path.
> >
> > kernel/irq/timings.c
> irq/timings.c is much more complicated, especially it applies EWMA to
> compute each irq's average interval. However, we only need it for
> do_IRQ() to cover all interrupt & softirq handler.

That does not justify yet another ad hoc thingy.

> Also CONFIG_IRQ_TIMINGS is usually disabled on distributions.

That's not an argument at all.