Re: [Qemu-devel] [PATCH v3 for-2.11 1/3] tpm_emulator: Add a caching layer for the TPM Established flag

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

On 11/15/2017 04:05 AM, Valluri, Amarnath wrote:
> On Wed, 2017-11-15 at 04:47 +0100, Marc-André Lureau wrote:
>> Hi
>>
>> On Wed, Nov 15, 2017 at 2:16 AM, Stefan Berger
>> <stefanb@linux.vnet.ibm.com> wrote:
>>> On 11/14/2017 06:40 PM, Marc-André Lureau wrote:
>>>>
>>>> Hi
>>>>
>>>> On Tue, Nov 14, 2017 at 10:52 PM, Stefan Berger
>>>> <stefanb@linux.vnet.ibm.com> wrote:
>>>>>
>>>>> Add a caching layer for the TPM established flag so that we
>>>>> don't
>>>>> need to go to the emulator every time the flag is read by
>>>>> accessing
>>>>> the REG_ACCESS register.
>>>> What's the impact? Isn't this just a "small" optimization? Iotw,
>>>> why
>>>> is this for-2.11?
>>> The TIS has a register that contains this flag and that's being
>>> polled quite
>>> frequently. So it generates a lot of traffic to the emulator. This
>>> caching
>>> layer gets rid of most of the traffic.
>> I didn't notice any problem when doing my tests, I guess Amarnath
>> niether. perhaps it's best to delay for after 2.11.
> Yes, I could see there is little frequent(21 calls to backend) to get
> establish flag, and this patch will help to avoid them. But i still
> agree with Marc and tag this as "small" optimization.

Can you review it so we have it ready for 2.12?

   Thanks,
       Stefan

>
> - Amarnath