From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH v5] KVM: VMX: Execute WBINVD to keep data consistency
 with assigned devices
Date: Tue, 29 Jun 2010 16:50:49 +0300
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Cc: Sheng Yang <sheng@linux.intel.com>,
	Jan Kiszka <jan.kiszka@siemens.com>,
	Joerg Roedel <joerg.roedel@amd.com>, kvm@vger.kernel.org,
	"Yaozu (Eddie) Dong" <eddie.dong@intel.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
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On 06/29/2010 04:35 PM, Marcelo Tosatti wrote:
>>>
>>> work_on_cpu() loop instead of smp_call_function_many(), to avoid executing
>>> wbinvd with interrupts disabled.
>>>        
>> Why?  wbinvd is not interruptible.
>>      
> Right. But still, smp_call_function_many() is going to busy-spin until
> the target CPUs finish their work, while work_on_cpu() will schedule.
>
>    

Good point.  So in the worst case we double the hit.

> Also the IPI request has to handled immediately, bypassing the
> scheduler.
>    

We're screwed on that point in any case, once wbinvd starts the 
scheduler is bypassed.

But work_on_cpu() has its own problems.  It creates a kthread (perhaps 
not too bad).  Maybe queue_work_on()?

btw, smp_call_function_many() appears not to run the function on the 
current cpu.

-- 
error compiling committee.c: too many arguments to function