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[Bug kprobes/2062] Return probes does not scale well on SMP box
- From: "guanglei at cn dot ibm dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 8 Jul 2006 05:14:09 -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 guanglei at cn dot ibm dot com 2006-07-08 05:14 -------
(In reply to comment #18)
>
> This looks correct -- Thanks! -- except that it appears you've introduced
> spaces, in some places, where there should be tabs. Grep for " " (7
> consecutive spaces).
sorry, because I used mouse to copy/paste your codes
(In reply to comment #18)
> Created an attachment (id=1149)
--> (http://sourceware.org/bugzilla/attachment.cgi?id=1149&action=view)
> kprobes module - equivalent of 'probe syscall.getsid.return {}'
>
> Guanglei, could you please re-run your test with this module inserted, rather
> than the SystemTap script running? Thanks.
I tested using stap and the module generated from getsid.c separately. I ran
each test about 4 times, here are the results:
====== 2.6.17.3/ppc64/8-way, without Jim's patch ================
no probe
Total cpus: loops = 40000000, average = 6202 ns
kretprobe using stap:
Total cpus: loops = 40000000, average = 43702 ns
kretprobe using getsid.c:
Total cpus: loops = 40000000, average = 36456 ns
======= 2.6.17.4/ppc64/8-way, with Jim's patch ===================
kretprobe using stap:
Total cpus: loops = 40000000, average = 26621 ns
kretprobe using getsid.c:
Total cpus: loops = 40000000, average = 24975 ns
==================================================================
The tests shows that the patch could help the performance improvement( ~30%
improvement), but kretprobe is still expensive.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=2062
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