Re: [PATCH 9/9] mmc: Convert from tasklet to BH workqueue

Tejun Heo
2024-03-28T16:21:36Z

Hello,

On Thu, Mar 28, 2024 at 01:53:25PM +0100, Ulf Hansson wrote:
> At this point we have suggested to drivers to switch to use threaded
> irq handlers (and regular work queues if needed too). That said,
> what's the benefit of using the BH work queue?

BH workqueues should behave about the same as tasklets which have more
limited interface and is subtly broken in an expensive-to-fix way (around
freeing in-flight work item), so the plan is to replace tasklets with BH
workqueues and remove tasklets from the kernel.

The [dis]advantages of BH workqueues over threaded IRQs or regular threaded
workqueues are the same as when you compare them to tasklets. No thread
switching overhead, so latencies will be a bit tighter. Wheteher that
actually matters really depends on the use case. Here, the biggest advantage
is that it's mostly interchangeable with tasklets and can thus be swapped
easily.

Thanks.

--
tejun