what is the default frequency and default event period set in "perf record -TP"

what is the default frequency and default event period set in "perf record -TP"

[Peipei Wang]

Hi all/David,

I want to know the frequency in the following command:
        perf record -e cycles -e cache-misses -e cache-references -TP
-o abc.data command

I looked up in the perfwiki, and it says the default value is 1000.
However, when I specify this parameter in the above command,that is,
"perf record -e cycles -e cache-misses -e cache-references -TP -F 1000
-o abc.data command", I found a significant difference between the
file data size.

Using the first command, the size of "abc.data" is about 500MB, but
the second command could generate the raw data size up to over 10GB.


I could not figure out the reason. Is it might because sampling mode
of cycles is based on frequency while the other two events are based
on event period?


Best wishes.
Yours,
Wang Peipei

Re: what is the default frequency and default event period set in "perf record -TP"

[David Ahern]

On 11/6/13, 4:52 PM, Peipei Wang wrote:
> Hi all/David,
>
> I want to know the frequency in the following command:
>          perf record -e cycles -e cache-misses -e cache-references -TP
> -o abc.data command
>
> I looked up in the perfwiki, and it says the default value is 1000.
> However, when I specify this parameter in the above command,that is,
> "perf record -e cycles -e cache-misses -e cache-references -TP -F 1000
> -o abc.data command", I found a significant difference between the
> file data size.
>
> Using the first command, the size of "abc.data" is about 500MB, but
> the second command could generate the raw data size up to over 10GB.
>
>
> I could not figure out the reason. Is it might because sampling mode
> of cycles is based on frequency while the other two events are based
> on event period?


default frequency was bumped to 4000 about a year ago. Not sure how the 
-F is impacting the cache-xxxx events.

David