Re: floating point support in the driver.

[Laurent Pinchart <laurentp@cse-semaphore.com>]

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On Friday 01 August 2008, Misbah khan wrote:
> 
> Hi all,
> 
> I have a DSP algorithm which i am running in the application even after
> enabling the VFP support it is taking a lot of time to get executed hence 
> 
> I want to transform the same into the driver insted of an user application.
> Can anybody suggest whether doing the same could be a better solution and
> what could be the chalenges that i have to face by implimenting such
> floating point support in the driver.
> 
> Is there a way in the application itself to make it execute faster.

Floating-point in the kernel should be avoided. FPU state save/restore operations are costly and are not performed by the kernel when switching from userspace to kernelspace context. You will have to protect floating-point sections with kernel_fpu_begin/kernel_fpu_end which, if I'm not mistaken, disables preemption. That's probably not something you want to do. Why would the same code run faster in kernelspace then userspace ?

-- 
Laurent Pinchart
CSE Semaphore Belgium

Chaussee de Bruxelles, 732A
B-1410 Waterloo
Belgium

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