On 8 September 2016 at 10:11, liubowen (A) <liubowen2@huawei.com> wrote:

Hi Mathieu:

   I am bob. And thanks for your time as always!

   In the past for a while, I worked based on our kernel and applied the patches about coresight from “perf-opencsd-4.7”. However, it is not successful.

So, I work based on your kernel “perf-opencsd-4.7”, and add some drivers about the board made from Hisilicon. In theory, it should go well. But I get the

same error. When I use perf to record data, the record will stop for a long time. And I check the source code and the program will stay in “perf_evlist__poll”

and do not return just as follow.



   So I use “Ctrl + C” to stop record, and I get the bug as follow.

You are not giving a command to trace - perf won't stop recording (everything that's happening on the system) until you kill it. Try a simple command like "uname" or "ls", the command should come back. Even then you'll have to use filters, which are present in v4.8-rc1 branch.

   On the other hand, I do a test as follow.





   In the source code, when we use the ETR mode, it will allocate 1M space as follow.



So, the coresight turns out to work well. Here, I have another question, when I change “SZ_1M” to a value bigger than 1M such as “SZ_2M”, and I try to enable

the etr device, I get the error “cannot allocate memory”.

I have used 2M many times myself without any issues. I'm pretty sure memory is not that low on your system - otherwise not much could run. I suggest you instrument the code to see where the failure comes from. I can't do much to help you here.

And I am sorry to trouble you, can you give me some suggestion? It really take a lot of my time to work on the project, I hope I can success finally.

From where I stand things seem to work on your system. It's just a matter of getting more familiar with coresight.

   Thanks very much for your time and all your help!!

   Best regards!

   Bob