On 07/22/2011 02:46 PM, Stefan Hajnoczi wrote:
Currently both perf and trace-cmd cannot parse the kvm:kvm_exit trace event
format. This patch is an attempt to make formatting work without changing the
kvm:kvm_exit prototype. Since this event is a core KVM operation, no doubt
there are existing trace analysis scripts that rely on it and I don't want to
break them.
Patch 1 adjusts vmexit-related tracepoints so that they can be fixed too.
Patch 2 replaces ftrace_print_symbols_seq() with __print_symbolic(). This
means all information necessary for formatting the exit_reason field is now
part of the trace event's format. In theory userspace tools should now work.
Thanks, applied.
In practice both perf and trace-cmd are not happy with the new exit_reason
formatting expression (omitting the details and split across lines for easy
email reading here):
print fmt: "reason %s rip 0x%lx info %llx %llx",
(REC->isa == 1) ?
__print_symbolic(REC->exit_reason, { 0, "EXCEPTION_NMI" }, ...) :
__print_symbolic(REC->exit_reason, { 0x000, "read_cr0" }, ...),
REC->guest_rip, REC->info1, REC->info2
perf script says:
Warning: Error: expected type 5 but read 4
Warning: Error: expected type 5 but read 0
Warning: unknown op '}'
kvm 2696 [001] 289.850941: kvm_exit: EVENT 'kvm_exit' FAILED TO PARSE
trace-cmd says:
Error: expected type 5 but read 4
Error: expected type 5 but read 0
failed to read event print fmt for kvm_exit
kvm-2696 [000] 1451.564092: kvm_exit: [FAILED TO PARSE] exit_reason=44 guest_rip=0xc01151a8 isa=1 info1=4272 info2=0
I'd really like to make perf and trace-cmd just work with kvm:kvm_exit. Any
suggestions other than improving the parsers in the respective tools?
trace-cmd has a plugin API (and a kvm plugin) that you can use for this,
and I expect perf either does as well or can make use of one. I don't
think it's useful to complicate the print format description further to
support our weird use case.
--
error compiling committee.c: too many arguments to function
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