Re: [PATCH v3 1/2] perf/kvm: Port perf kvm to powerpc
From: Scott Wood
Date: Mon May 11 2015 - 18:08:59 EST
On Fri, 2015-05-08 at 06:37 +0530, Hemant Kumar wrote:
> From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
> perf kvm can be used to analyze guest exit reasons. This support already
> exists in x86. Hence, porting it to powerpc.
> - To trace KVM events :
> perf kvm stat record
> If many guests are running, we can track for a specific guest by using
> --pid as in : perf kvm stat record --pid <pid>
> - To see the results :
> perf kvm stat report
> The result shows the number of exits (from the guest context to
> host/hypervisor context) grouped by their respective exit reasons with
> their frequency.
> This patch makes use of the guest exit reasons available in
> "trace_book3s.h". It records on two already available tracepoints :
> "kvm_hv:kvm_guest_exit" and "kvm_hv:kvm_guest_enter".
> Note : This patch has a dependency on the patch "kvm/powerpc: Export
> kvm exit reasons" which exports the KVM exit reasons through the uapi.
> Here is a sample o/p:
> # pgrep qemu
> 2 Guests are running on the host.
> # perf kvm stat record -a
> ^C[ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 4.153 MB perf.data.guest (39624 samples) ]
> # perf kvm stat report -p 60515
> Analyze events for pid(s) 60515, all VCPUs:
> VM-EXIT Samples Samples% Time% Min Time Max Time Avg time
> H_DATA_STORAGE 5006 35.30% 0.13% 1.94us 49.46us 12.37us ( +- 0.52% )
> HV_DECREMENTER 4457 31.43% 0.02% 0.72us 16.14us 1.91us ( +- 0.96% )
> SYSCALL 2690 18.97% 0.10% 2.84us 528.24us 18.29us ( +- 3.75% )
> RETURN_TO_HOST 1789 12.61% 99.76% 1.58us 672791.91us 27470.23us ( +- 3.00% )
> EXTERNAL 240 1.69% 0.00% 0.69us 10.67us 1.33us ( +- 5.34% )
> Total Samples:14182, Total events handled time:49264158.30us.
> Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Hemant Kumar <hemant@xxxxxxxxxxxxxxxxxx>
> Patch has a dependency on : https://patchwork.ozlabs.org/patch/469839/
> which exports the exit reasons to perf through uapi.
> - Original series split into two patchsets now : perf and powerpc
> side changes.
> arch/powerpc/include/uapi/asm/kvm_perf.h | 15 +++++++++++++++
> tools/perf/arch/powerpc/Makefile | 1 +
> tools/perf/arch/powerpc/util/Build | 1 +
> tools/perf/arch/powerpc/util/kvm-stat.c | 33 ++++++++++++++++++++++++++++++++
> 4 files changed, 50 insertions(+)
> create mode 100644 arch/powerpc/include/uapi/asm/kvm_perf.h
> create mode 100644 tools/perf/arch/powerpc/util/kvm-stat.c
> diff --git a/arch/powerpc/include/uapi/asm/kvm_perf.h b/arch/powerpc/include/uapi/asm/kvm_perf.h
> new file mode 100644
> index 0000000..30fa670
> --- /dev/null
> +++ b/arch/powerpc/include/uapi/asm/kvm_perf.h
> @@ -0,0 +1,15 @@
> +#ifndef _ASM_POWERPC_KVM_PERF_H
> +#define _ASM_POWERPC_KVM_PERF_H
> +#include <asm/trace_book3s.h>
> +#include <asm/kvm.h>
> +#define DECODE_STR_LEN 20
> +#define VCPU_ID "vcpu_id"
> +#define KVM_ENTRY_TRACE "kvm_hv:kvm_guest_enter"
> +#define KVM_EXIT_TRACE "kvm_hv:kvm_guest_exit"
> +#define KVM_EXIT_REASON "trap"
> +#endif /* _ASM_POWERPC_KVM_PERF_H */
Please make sure that anything book3s-specific is named that way.
And shouldn't this be part of the arch/powerpc-side patchset?
> diff --git a/tools/perf/arch/powerpc/Makefile b/tools/perf/arch/powerpc/Makefile
> index 7fbca17..21322e0 100644
> --- a/tools/perf/arch/powerpc/Makefile
> +++ b/tools/perf/arch/powerpc/Makefile
> @@ -1,3 +1,4 @@
> ifndef NO_DWARF
> PERF_HAVE_DWARF_REGS := 1
> +HAVE_KVM_STAT_SUPPORT := 1
Does this stuff fail gracefully if used on a PPC target that doesn't
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