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[Bug testsuite/11514] nd_syscall.exp takes more than 10 times longer than syscall.exp testcase
- From: "mjw at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sources dot redhat dot com
- Date: 20 Apr 2010 14:55:50 -0000
- Subject: [Bug testsuite/11514] nd_syscall.exp takes more than 10 times longer than syscall.exp testcase
- References: <20100419113044.11514.mjw@redhat.com>
- Reply-to: sourceware-bugzilla at sourceware dot org
------- Additional Comments From mjw at redhat dot com 2010-04-20 14:55 -------
(In reply to comment #8)
> (In reply to comment #7)
> > Resolving them all in one go with kallsyms_on_each_symbol() just before
> > registering then in kprobe_derived_probe_group::emit_module_init() seems the
> > quickest way to speed this up.
>
> Frank correctly pointed out on irc that this isn't a speedup, but jus flips the
> comparison loop inside out. We still need to compare all kallsyms symbols
> against all kprobe symbol names. So we still end up with O(N*M) comparisons. So
> to speed up we really need to be using more clever data structures.
Except that most time seems to go into kallsyms_expand_symbol to uncompress the
kernel symbol table. So flipping the comparison loop inside out to only do that
once might still be a win.
--
http://sourceware.org/bugzilla/show_bug.cgi?id=11514
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