Re: [Xen-devel] [PATCH v2 09/13] optee: add support for arbitrary shared memory

[Julien Grall <julien.grall@xxxxxxx>]

On 09/12/2018 01:45 PM, Volodymyr Babchuk wrote:
> Hi,
Hi Volodymyr,

> On 12.09.18 14:02, Julien Grall wrote:
> > On 09/11/2018 08:33 PM, Volodymyr Babchuk wrote:
> > > > However, 2MB might be too big considering that you also need to 
> > > > account the SMC call. Does buffer can be passed for fast call?
> > > No, all such calls are yielding calls, so you can ignore time used 
> > > for SMC call itself.
> > How come you can ignore it? It has a cost to trap to EL3.
> Strictly speaking, yes. All steps has cost: trap to EL3, dispatch in EL3,
> switch to S-EL1, new thread preparation in OP-TEE, context switch in 
> OP-TEE.
> I wanted to tell, that in my opinion, this is negligible in comparison 
> with the actual call processing. But maybe, I'm wrong there.
It would be interesting to have a breakdown on the time spent in the 
call (with virtualization). Did you have a chance to do that?
Cheers,

--
Julien Grall

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