On Fri, Apr 8, 2011 at 7:53 PM, David Ahern <dsahern@xxxxxxxxx> wrote:
> 2.6.38.2 kernel with trace-cmd git pulled this morning:
>
> trace-cmd record -e kvm
>
> trace-cmd report 2>&1 | less
>
> trace-cmd: No such file or directory
> function ftrace_print_symbols_seq not defined
> failed to read event print fmt for kvm_nested_vmexit_inject
> function ftrace_print_symbols_seq not defined
> failed to read event print fmt for kvm_nested_vmexit
> function ftrace_print_symbols_seq not defined
> failed to read event print fmt for kvm_exit
> bad op token {
> failed to read event print fmt for kvm_emulate_insn
>
> qemu-kvm-1864 [002] 2253.714134: kvm_entry: vcpu 1
> qemu-kvm-1863 [008] 2253.714136: kvm_exit: [FAILED
> TO PARSE] exit_reason=44 guest_rip=0xc01185ed isa=1 info1=4272 info2=0
> qemu-kvm-1864 [002] 2253.714138: kvm_exit: [FAILED
> TO PARSE] exit_reason=44 guest_rip=0xc01185ed isa=1 info1=4272 info2=0
> qemu-kvm-1863 [008] 2253.714145: kvm_emulate_insn: [FAILED
> TO PARSE] rip=3222373869 csbase=0 len=2 insn=<89>^H]<C3><8B>^U<EC><95>K<C0>U
> <89><E5>]<8D>^E flags=5 failed=0
>
> I have not used trace-cmd much, so I am not familiar with the code. Is
> this a known issue? Suggestions on how to debug?
I think there have been issues for a long time. I've never gotten
perf or trace-cmd to be happy with kvm:* events. Here is a related
thread from a while back:
https://lkml.org/lkml/2010/5/26/194
When I looked a while back the problem was due to how there is some
preprocessor magic in Linux that ends up exporting C expressions as
strings to userspace and neither perf nor trace-cmd have the parsing
smarts to evaluate the C expressions at runtime.
I ended up using ftrace instead which handles everything inside the
kernel and compiles in those C expressions.
Stefan
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