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SubjectRe: [RFC PATCH 0/6] Convert all tasklets to workqueues
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On Mon, 2007-06-25 at 18:00 -0600, Jonathan Corbet wrote:
> A couple of days ago I said:
>
> > The cafe_ccic (OLPC) camera driver uses a tasklet to move frames out of
> > the DMA buffers in the streaming I/O path....
> >
> > Obviously some testing is called for here. I will make an attempt to do
> > that testing
>
> I've done that testing - I have an OLPC B3 unit running V2 of the
> tasklet->workqueue patch, and all seems well. 30 FPS to the display and
> no dropped frames. The tasklets/0 process is running 3-5% CPU, in case
> that's interesting. For whatever reason, I see about 3% *more* idle
> time when running just mplayer than I did without the patch.
>
> Consider my minor qualms withdrawn, there doesn't seem to be any trouble
> in this area.

Jon, thanks a lot!

This is great news. I wonder if converting tasklets to work queues also
helps with other softirqs. Before, softirqs could not preempt a
tasklet, since tasklets run as a softirq. With tasklets as work queues,
what's left as a softirq can now preempt tasklets. Perhaps this can even
help with performance.

-- Steve


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