Re: [Xen-ia64-devel] [PATCH] bug fix new_tlbflush_clock_period()

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Mon, Feb 05, 2007 at 01:11:38PM +0800, Xu, Anthony wrote:
> Yes, there is no correctness issue.
> But it is a waste of time to call local_vhpt_flsh if it is unnecessary.
> 
> And if CONFIG_XEN_IA64_PERVCPU_VHPT is defined,
> Vhpt_init should not allocate per-pcpu vhpt, it is a waste of memory.

It consumes only several mega bytes (We can assume at least
several giga bytes on a box.) and the tlb flush clock overflow
would takes very long time.
The current implementation is intended to allow per-vcpu vhpt
domain coexist with per-pcpu vhpt domain.
Currently we can only turn off per-vcpu vhpt system widely with
"pervcpu_vhpt" boot option.
The only missing part is how to pass the user configuration to xen
domain creation and initialize it in per-domain fashion.

So your proposal is to remove such dynamic checks and
make the per-vcpu vhpt code compile-time-only configuration.
Or to allocate per-pcpu vhpt when per-pcph vhpt domain is created
and to add check if per-pcph vhpt is allocated.
Do you think it's worth while?
-- 
yamahata

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