Re: [RFC 1/1] drivers/dma/*: replace tasklets with workqueue

Arnd Bergmann
2022-05-31T18:02:39Z

On Tue, May 31, 2022 at 7:02 PM Allen Pais <apais@linux.microsoft.com> wrote:

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> > That is a good idea, lot of drivers are waiting for completion which can
> > be signalled from hardirq, this would also reduce the hops we have and
> > help improve latency a bit. On the downside, some controllers provide
> > error information, which would need to be dealt with.
>
>
> I am not an expert in dma subsystem, but by using completion from
> Hardirq context be a concern? Especially with latency.

I don't see how: to the task waiting for the completion, there should
be no difference, and for the irq handler sending it, it just avoids
a few cycles going into softirq context.

> > Yes that would be a very reasonable mechanism, thanks for the
> > suggestions.
>
> I have started working on the idea of global softirq. A RFC should be ready
> For review soon.

Ok, thanks!

Arnd