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

[Hemant Kumar]

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

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