Re: [PATCHv8 2/5] arm64: dts: qcom: msm8998: Add Coresight support

Sai Prakash Ranjan
2019-07-18T09:54:05Z

Hi,

On 7/18/2019 3:07 PM, Suzuki K Poulose wrote:
>
>
> Using the sysfs doesn't guarantee that the ETR actually uses SG mode,
> unless
> the buffer size selected is > 1M, which is why I am more interested in the
> perf usage. Alternatively you may configure a larger buffer size (say,
> 8MB) via:
>
> echo 0x800000 > /sys/bus/coresight/.../tmc_etr0/buffer_size
>

Yes, you had mentioned about setting buffer size > 1M in the same
thread[1] and I had followed the same.

[1] https://lkml.org/lkml/2019/1/18/311

>
>>
>> As said in one of the series initially [1], QCOM msm downstream kernels
>> have been using scatter gather mode and we haven't seen any fatal issues.
>>
>> [1] https://patchwork.kernel.org/patch/10769535/
>
> I haven't seen any test results there either.
>

You did not ask for it there ;)

I do not have the test results handy now and those platforms.
I will arrange for them and post some test results.

Just to confirm, do you need some traces or just the buffer size
and sink set?

Thanks,
Sai