From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: trace-cmd errors on kvm events Date: Fri, 08 Apr 2011 14:59:34 -0600 Message-ID: <4D9F7736.4070509@gmail.com> References: <4D9F59AC.6080707@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: LKML , KVM mailing list To: Stefan Hajnoczi Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/08/11 14:50, Stefan Hajnoczi wrote: > On Fri, Apr 8, 2011 at 7:53 PM, David Ahern 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]<8B>^U<95>KU >> <89>]<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. Hmm.. ok. I thought it had been added - to trace-cmd at least. And I recall Avi recently sending a patch to trace-cmd folks - I took that to mean it works. Evidently, not. David > > I ended up using ftrace instead which handles everything inside the > kernel and compiles in those C expressions. > > Stefan