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[Bug kprobes/2062] Return probes does not scale well on SMP box
- From: "anil dot s dot keshavamurthy at intel dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 18 Apr 2006 20:38:16 -0000
- Subject: [Bug kprobes/2062] Return probes does not scale well on SMP box
- References: <20051216010933.2062.anil.s.keshavamurthy@intel.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From anil dot s dot keshavamurthy at intel dot com 2006-04-18 20:38 -------
> why not just store data per cpu/core
Storing it in per cpu might not work here as in some cases the function enter
might be called on one cpu and the by the time that function returns it could
have migrated to a different cpu's and hence return is executed from different
cpu. So we have to do global search for the return probe instance related to
that perticular task and hence per cpu/core is not feasible.
However if we store the return probe instances in the task structure itself(by
extending the task struct)then we can completly eliminate the locks for return
probes and return probes can be made to run in parallel. We have to convince
the linux community for extension of task struct.
-Anil
--
http://sourceware.org/bugzilla/show_bug.cgi?id=2062
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