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@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
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@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.
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
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--
Thanks,
Hemant Kumar
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