Re: High-priority softirqs [was: [PATCH] usb: don't offload isochronous urb completions to ksoftirq]

From: Sebastian Sewior
Date: Fri Jun 15 2018 - 13:40:23 EST

On 2018-06-15 13:34:28 [-0400], Steven Rostedt wrote:
> On Fri, 15 Jun 2018 19:28:34 +0200 (CEST)
> Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > One solution to that is to avoid both tasklets and kworkers and change the
> > USB code to make use of threaded interrupt handlers. I.e. handle the fast
> > stuff in the primary (hardirq) handler and delegate the rest to the irq
> > thread. That thread still can offload disk type stuff to a kworker if
> > needed. But the irq thread allows to bring the stuff under scheduler
> > control and experiments which I did a few years ago worked out pretty good.
> If there's any question about this, drivers can request to have their
> interrupt handlers run as threads. This has been added to mainline
> years ago. And it really should be the default solution before pushing
> off to tasklets or kworkers.

> -- Steve