Messages in this thread | | | Subject | Re: Scheduling tasklets from process context... | From | Roland Dreier <> | Date | Wed, 06 Apr 2005 09:46:17 -0700 |
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arun> Since tasklets are typically used for bottom half arun> processing, is it acceptable/recommended that they be arun> scheduled from a process context (say an ioctl handler)?
arun> Should one try to minimize such scheduling and try to do arun> things in process context if possible, as tasklets run in arun> interrupt context? Or is the driver writer free to use the arun> tasklets at will? What is recommended here?
I guess it would work to schedule a tasklet from your ioctl handler, but I don't see a good reason to do it. What are you really trying to do?
Your ioctl handler runs in process context so you are free to do pretty much anything -- allocate with GFP_KERNEL, sleep, etc. If you want to return to userspace immediately but defer some work until later, it would probably make more sense to use something like schedule_work() instead of a tasklet.
The main point of tasklets is that they run at a high priority, very soon after they're scheduled, so that an interrupt handler can return quickly by deferring work to a tasklet but still not add too much latency. But in your ioctl handler, if you have some high priority work, you can just do it immediately without the complication of a tasklet.
- R.
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