Jeff Mahoney píše v Út 19. 04. 2011 v 15:39 -0400:
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Hi all -
Bnc#656091 asks about enabling UTRACE for other kernel flavors. It's too
late to do it for 11.4 since enabling it modifies struct task_struct.
However, most of the trace infrastructure appears to use jump labels
now, which means that they're essentially free when not in use.
I'd like to eliminate the trace flavor for the 12.1 release. At this
point the only differences are ftrace and utrace.
Has anyone done the legwork to verify the performance impact here? I
suppose since it's only in Factory for now we can just change it and see
what shakes out.
I'll only talk about the utrace part.
First, bug 656091 says that CONFIG_UTRACE is needed for systemtap to
work. This is not true. Or rather, it's true only if you specifically
enable utrace support in systemtap.
Second, UTRACE has never been and will never be accepted in mainline,
AFAICS. OTOH, since it's a Redhat-specific out-of-tree patch, it might
be requested by PM anyway to achieve "RHEL parity".
Third, the utrace project seems to be dead (or at least on hold since
December where all traffic stopped on the utrace-devel mailing list).
This raises lots of concern about the future of the UTRACE patch.
Fourth, what do you mean by "it's only in Factory"? CONFIG_UTRACE is
certainly not enabled for vanilla or default, is it?
At this point, if you want to reduce the number of flavours, I vote for
dropping the UTRACE patch. It's bad enough I'll have to maintain it for
the SLE11 branch.