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List:       linuxppc-embedded
Subject:    Re: Linux kernel thread with Linux 2.6.x
From:       Andy Fleming <afleming () freescale ! com>
Date:       2006-05-30 22:10:14
Message-ID: 72927AD7-DCFD-470E-A9FD-D3BE10100D53 () freescale ! com
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Couldn't you use a work_queue?  For the PHY Layer, the MDIO  
transactions can't occur at interrupt time (they need to be  
interruptible), so the interrupt handler calls schedule_work() to get  
the interrupt handled.  I'm not sure how much faster it is (if at  
all), but it's another method, and sounds less complicated than  
waiting on a semaphore.

Of course, I would suggest trying to avoid the buffer allocation  
functions you are using, or defer the work using NAPI, but it's  
impossible for me to tell whether that's a reasonable solution for you.

On May 29, 2006, at 10:35, Laurent Lagrange wrote:

>
> Hello everybody,
>
> I'm writing a custom network driver based on a MPC8260 FCC device  
> for a
> 2.6.9 linux kernel.
> In this driver, I need to use specific buffer allocation functions  
> which use
> down and up semaphore functions.
>
> As the interrupt handler can't be scheduled, I have made a kernel  
> thread
> which waits forever on a semaphore.
> This semaphore is set when a received packet interrupt occured. All  
> that
> mechanism works but the performances
> are very poor.
>
> Is there any solution to increase the kthread priority in the  
> scheduler ?
> Is there another solution than the semaphore to quickly wake up a  
> kthread ?
>
> Thanks a lot for your help.
> Laurent
>
>
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> Linuxppc-embedded@ozlabs.org
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