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From: Tom Tromey <tromey@redhat.com>
To: Pedro Alves <pedro@codesourcery.com>
Cc: gdb-patches@sourceware.org, Sergio Durigan Junior <sergiodj@redhat.com>
Subject: Re: [PATCH 3/6] Modify internalvar mechanism
Date: Tue, 19 Apr 2011 20:01:00 -0000	[thread overview]
Message-ID: <m3fwpe3tas.fsf@fleche.redhat.com> (raw)
In-Reply-To: <m3oc423x1y.fsf@fleche.redhat.com> (Tom Tromey's message of "Tue,	19 Apr 2011 12:39:37 -0600")

Pedro> I noticed that patch 4 does some changes to 
Pedro> start_tracing to tweak the probes' semaphores, if any.
Pedro> What are these semaphores?  How do other stap tools
Pedro> handle them?  I ask because that bends a bit the definition
Pedro> of "trace" being a regular tracepoint at a given
Pedro> location, so I'd like to understand it.

While developing this, Sergio and I talked extensively to Roland and the
other SystemTap guys about the sdt.h implementation.  Today I finally
got around to writing up our notes:

http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation

There is already some documentation about adding probes:

http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps

.. though it seems to focus a bit too much (IMO) on the dtrace
compatibility aspect.  You can see a simpler approach in the test suite
part of patch #4 -- you don't actually need anything more than the
#include.

Tom


      reply	other threads:[~2011-04-19 20:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-04-04  3:08 Sergio Durigan Junior
2011-04-11 21:08 ` Jan Kratochvil
2011-04-12 11:24 ` Pedro Alves
2011-04-12 20:40   ` Tom Tromey
2011-04-12 22:33   ` Sergio Durigan Junior
2011-04-19 17:53     ` Pedro Alves
2011-04-19 18:40       ` Tom Tromey
2011-04-19 20:01         ` Tom Tromey [this message]

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