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SubjectRe: [PATCH v3 1/2] perf/kvm: Port perf kvm to powerpc
Hi Scott,

On 05/12/2015 03:38 AM, Scott Wood wrote:
> On Fri, 2015-05-08 at 06:37 +0530, Hemant Kumar wrote:
>> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
>>
>> 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
>> 19378
>> 60515
>>
>> 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@linux.vnet.ibm.com>
>> Signed-off-by: Hemant Kumar <hemant@linux.vnet.ibm.com>
>> ---
>> Patch has a dependency on : https://patchwork.ozlabs.org/patch/469839/
>> which exports the exit reasons to perf through uapi.
>>
>> Changes:
>> - 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.

Are you suggesting to name it to something like _ASM_POWERPC_BOOK3S_PERF_H ?

> And shouldn't this be part of the arch/powerpc-side patchset?

It should. Thanks, will move this to 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
>> endif
>> +HAVE_KVM_STAT_SUPPORT := 1
> Does this stuff fail gracefully if used on a PPC target that doesn't
> support this?

Yes, it does.

> -Scott
>
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

--
Thanks,
Hemant Kumar



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