Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:

[Hemant Kumar <hkshaw@linux.vnet.ibm.com>]

On 10/29/2013 07:35 PM, Pekka Enberg wrote:
> On 10/29/2013 11:55 AM, Hemant Kumar wrote:
>> 1. Where this cache should be? Keeping it in tracing directory inside 
>> the debugfs
>> directory should seem more feasible. And, shall this cache be shareable?
>
> You can't share all of the cache because otherwise you'll expose 
> details on binaries that not everyone has access to.

Correct, that was one of the reason to be worried. And since, to a 
normal user debugfs is not allowed to be entered, then we can keep that 
inside debugfs/tracing subdirectory.

>
> It might make sense to split the cache into two parts: system markers 
> and user markers and share the former.
>

Ok...

>> 2. perf record is a performance intensive process, can we allow the 
>> delay due to
>> this searching process here?
>
> I think scanning is OK if the user specified a SDT markers but not 
> otherwise.
>
> Perhaps you can use a bloom filter to quickly check if the user passed 
> a SDT marker or not.
>

True, bloom filters may help in this case with a quick check.

-- 
Thanks
Hemant Kumar