Re: [RFC PATCH 2/7] RDMA/rxe: Convert the triple tasklets to workqueues

[Yanjun Zhu]

在 2022/9/12 15:58, matsuda-daisuke@xxxxxxxxxxx 写道:
> On Mon, Sep 12, 2022 12:09 AM Bart Van Assche wrote:
> > On 9/11/22 00:10, Yanjun Zhu wrote:
> > > I also implemented a workqueue for rxe. IMO, can we add a variable to
> > > decide to use tasklet or workqueue?
> > >
> > > If user prefer using tasklet, he can set the variable to use
> > > tasklet. And the default is tasklet. Set the variable to another
> > > value to use workqueue.
> That's an interesting idea, but I am not sure how users specify it.
> IIRC, tasklets are generated when rdma link is added, typically by
> executing ' rdma link add' command. I don't think we can add
> an device specific option to the utility(iproute2/rdma).

In my workqueue implementation, I used a sysctl variable to set a value 
to choose tasklet or workqueue.

You can use sysctl or driver parameter to decide to use tasklet or 
workqueue.

And finally the Macros like #if ... #else ... #endif also acts as a method.

Zhu Yanjun

> > I'm in favor of removing all uses of the tasklet mechanism because of
> > the disadvantages of that mechanism. See also:
> > * "Eliminating tasklets" (https://lwn.net/Articles/239633/).
> > * "Modernizing the tasklet API" (https://lwn.net/Articles/830964/).
> > * Sebastian Andrzej Siewior's opinion about tasklets
> > (https://lore.kernel.org/all/YvovfXMJQAUBsvBZ@xxxxxxxxxxxxx/).
> I am also in favor of using workqueues alone not only because of the
> disadvantages above but also to avoid complexity. I would like to know
> if there is anybody who will bothered by the change especially in terms
> of performance.
>
> Thanks,
> Daisuke
>
> > Thanks,
> >
> > Bart.