RE: [Xen-ia64-devel] [PATCH] NEW_TLBFLUSH_CLOCK_PERIOD_SOFTIRQ is notregistered.

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Isaku Yamahata write on 2007年1月29日 17:21:
> On Mon, Jan 29, 2007 at 05:00:11PM +0800, Xu, Anthony wrote:
> It doesn't optimize NEED_FLUSH itself.
> The optimization path is executed when NEED_FLUSH return 0.
> See flush_vtlb_for_context_switch() @ xen/arch/ia64/xehn/domain.c.
> 
> When CONFIG_XEN_IA64_TLBFLUSH_CLOCK is defined,
> NEED_FLUSH() always returns 1. No optimization.
> Suppose that CONFIG_XEN_IA64_TLBFLUSH_CLOCK is defined and
> NEED_FLUSH() returns 0.
> In that case, we can skip local_vhpt_flush() or local_flush_tlb_all().

Hi Isaku,

Thanks for your explanation.  

Suppose that CONFIG_XEN_IA64_TLBFLUSH_CLOCK is defined
NEED_FLUSH() returns 0.
 In that case, we can skip local_vhpt_flush() or local_flush_tlb_all().

But the skip is on the cost of new_tlbflush_clock_period calling 
vcpu_vhpt_flush.

Anyway, vcpu_vhpt_flush must be called, the difference is where it is called.

I don't see the benefit of new_tlbflush_clock_period.

I must miss something.



Can you explain more?

Thanks,
Anthony





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