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

From: Hemant Kumar
Date: Tue Oct 29 2013 - 15:41:38 EST


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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