MSR_SPE - being turned off...

[Kumar Gala]

Can you describe the # of processes you are running in your test.  Is  
it possible for you to try the tests w/2.6.29 from kernel.org?

- k

On May 6, 2009, at 7:42 AM, Morrison, Tom wrote:

> I'm sorry I forgot to put that, this issue was found with our
> currently running kernel 2.6.23.final (what comes with the
> Freescale LTIB BSP package dated 05/23/2009).
>
> I am sorry if I don't understand your statement that the SMP might
> be broken on this kernel, because I tried to analyze the kernel that
> came with the latest BSP LTIB [ackage from Freescale (dated 12/18/2009
> (where we got the 4.2.171 compiler from)), and the associated 'switch
> context' code is exactly the same. Unfortunately, I have not started
> the process of porting my current platform's BSP to this new kernel -
> otherwise, I would have done the test on that platform (this also
> requires a new version of u-boot in order to test correctly))..
>
> I may have mis-interpreted something and/or I am sure I don't
> understand everything about the SMP resource management (and
> associated SPE management), so thank you for any insight you
> may have on this front...
>
> Tom
>
>>> -----Original Message-----
>>> From: Kumar Gala [mailto:galak at kernel.crashing.org]
>>> Sent: Wednesday, May 06, 2009 8:32 AM
>>> To: Morrison, Tom
>>> Cc: Michael Neuling; linuxppc-dev at ozlabs.org
>>> Subject: Re: MSR_SPE - being turned off...
>>>
>>>
>>> On May 6, 2009, at 3:31 AM, Morrison, Tom wrote:
>>>
>>>> Kumar,
>>>>
>>>> What about the case of a context switch (i.e.: when things are
> setup
>>>> in registers for the SPE, but then a context switch happens before
>>>> the SPE is executed)?
>>>
>>> context switches will be fine.  What we normally do is keep track of
>>> which user app used SPE last and when some other app needs it we
> clear
>>> MSR_SPE for the old app, save its registers.  Than we load up the
>>> registers for the new app and set MSR_SPE.  When the old app context
>>> switches in it will get an SPE unavail exception at the point it
>>> executes its next SPE insn and we will repeat the process.
>>>
>>>> As to load_up_spe & give_up_spe, it was pointed out to me tonight
> by
>>>> a co-worker
>>>> to look at how things are saved in those routines, I definitely
> will
>>>> look at this again,
> c>> > and see how it is done...
>>>>
>>>> This is happening for us on an 8572 SMP. We are trying to get it to
>>>> happen
>>>> on 8548 (and single core 8572), but we haven't been able to push
>>>> this part
>>>> of the application as hard as it is being pushed on 8572...but we
>>>> will keep trying....
>>>
>>> Again, what kernel version for 8572?  Its possible old SMP kernels
> are
>>> broken on 8572.
>>>
>>> - k
>>>
>>>> ________________________________
>>>>
> <snip previous emails>