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RE: [Xen-ia64-devel] context switch bug ?


  • To: "Tristan Gingold" <Tristan.Gingold@xxxxxxxx>, <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>
  • Date: Mon, 26 Sep 2005 12:38:18 -0700
  • Delivery-date: Mon, 26 Sep 2005 19:35:52 +0000
  • List-id: Discussion of the ia64 port of Xen <xen-ia64-devel.lists.xensource.com>
  • Thread-index: AcXCsZu9IuTjtZz6QsGqUAu17JzF6QAIBOaQ
  • Thread-topic: [Xen-ia64-devel] context switch bug ?

I'm not sure if I'm misunderstanding, but the line
that is between context_switch and context_switch_finalize
is spin_UNLOCK_irq, which releases the lock, correct? 

> -----Original Message-----
> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf 
> Of Tristan Gingold
> Sent: Monday, September 26, 2005 10:50 AM
> To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-ia64-devel] context switch bug ?
> 
> Hi,
> 
> while working on SMP, I think I hit a problem which may 
> require a local 
> redesign in context switching.
> 
> In common/schedule.c(__enter_scheduler), the last lines are:
> 
>     context_switch(prev, next);
> 
>     spin_unlock_irq(&schedule_data[cpu].schedule_lock);
> 
>     context_switch_finalise(next);
> }
> 
> Unfortunatly, on ia64, context_switch does all the work and 
> context_switch_finalise does nothing.  Therefore, the cpu-spin lock is
> still taken when the domain runs [even with one cpu].
> It is correct ?
> 
> I will try to fix this issue tomorrow, and I will look on x86 
> code.  However, 
> if anymore has already think about this issue, please share!
> 
> Thanks.
> 
> _______________________________________________
> Xen-ia64-devel mailing list
> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
> 

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