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authorWei Huang <wei@redhat.com>2015-01-23 15:56:04 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2015-01-26 12:27:05 +0100
commitfc116efad0aadb2f8a49d51240bddbfe21b631a0 (patch)
treeb23457793d38d52d98f884ea96bc206a19fda762 /qemu-timer.c
parent13704e4c455770d500d6b87b117e32f0d01252c9 (diff)
downloadfocaccia-qemu-fc116efad0aadb2f8a49d51240bddbfe21b631a0.tar.gz
focaccia-qemu-fc116efad0aadb2f8a49d51240bddbfe21b631a0.zip
kvm_stat: Add RESET support for perf event ioctl
While running kvm_stat using tracepoint on ARM64 hardware (e.g. "kvm_stat
-1 -t"), the initial values of some kvm_userspace_exit counters were found
to be very suspecious. For instance the tracing tool showed that S390_TSCH
was called many times on ARM64 machine, which apparently was wrong.

This patch adds RESET ioctl support for perf monitoring. Before calling
ioctl to enable a perf event, this patch resets the counter first. With
this patch, the init counter values become correct on ARM64 hardware.

Example:

==== before patch ====
kvm_userspace_exit(S390_SIEIC)      1426         0
kvm_userspace_exit(S390_TSCH)       339         0

==== after patch ====
kvm_userspace_exit(S390_SIEIC)         0         0
kvm_userspace_exit(S390_TSCH)         0         0

Signed-off-by: Wei Huang <wei@redhat.com>
Diffstat (limited to 'qemu-timer.c')
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