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

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Message-Id: <F53BA283-A194-4057-8409-27FD3ECFDF2E@iki.fi>
Date:	Fri, 25 Oct 2013 16:20:54 +0200
From:	Pekka Enberg <penberg@....fi>
To:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Pekka Enberg <penberg@...nel.org>,
	Hemant Kumar <hkshaw@...ux.vnet.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Oleg Nesterov <oleg@...hat.com>,
	"hegdevasant@...ux.vnet.ibm.com" <hegdevasant@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	"anton@...hat.com" <anton@...hat.com>,
	"systemtap@...rceware.org" <systemtap@...rceware.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	"aravinda@...ux.vnet.ibm.com" <aravinda@...ux.vnet.ibm.com>
Subject: Re: [PATCH v4 2/3] Support for perf to probe into SDT markers:

> Technically feasible. But then we would have to parse each of the
> libraries and executables to list them. Right? I am not sure if such a
> delay is acceptable.

You could do it at 'perf list' time or even build time and cache it. And add lazy discovery to 'perf record' and friends.

> Also if a binary exists in a path thats is not covered in the default
> search, an user might believe that his binary may not have markers.
> I know the above reason is more of a user folly than a tooling issue.

Lazy discovery at 'perf record'-time from executable and DSOs should make that transparent to the user, no? I'm pretty sure it will be fast enough with content-adressed cache.

- Pekka--
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