Re: Softirq priority inversion from "softirq: reduce latencies"
From: Mike Galbraith
Date: Sun Feb 28 2016 - 00:56:18 EST
On Sat, 2016-02-27 at 10:19 -0800, Peter Hurley wrote:
> Hi Eric,
> For a while now, we've been struggling to understand why we've been
> observing missed uart rx DMA.
> Because both the uart driver (omap8250) and the dmaengine driver
> (edma) were (relatively) new, we assumed there was some race between
> starting a new rx DMA and processing the previous one.
Hrm, relatively new + tasklet woes rings a bell. Ah, that..
What's worse is that at the point where this code was written it was
already well known that tasklets are a steaming pile of crap and
Source thereof https://lwn.net/Articles/588457/