Changes in version 2:
- Fixed block comment formatting as requested by Ingo Molnar
- Changed commit summary to refer to a testcase that more easily shows the
problem.
For reference here's a complete testcase for an Intel TSX-enabled KVM guest:
#include <linux/perf_event.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <unistd.h>
int main(void) {
struct perf_event_attr attr;
int fd;
long long count;
memset(&attr, 0, sizeof(attr));
attr.type = PERF_TYPE_RAW;
attr.size = sizeof(attr);
attr.config = 0x2005101c4; // conditional branches retired IN_TXCP
attr.sample_period = 0;
attr.exclude_kernel = 1;
attr.exclude_guest = 1;
fd = syscall(__NR_perf_event_open, &attr, 0, -1, -1, 0);
ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);
ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);
for (int i = 0; i < 500; ++i) {
putchar('.');
}
read(fd, &count, sizeof(count));
printf("\nConditional branches: %lld\n%s\n", count,
count < 500 ? "FAILED" : "PASSED");
return 0;
}
Robert O'Callahan (1):
KVM: x86: never specify a sample period for virtualized in_tx_cp
counters
arch/x86/kvm/pmu.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
--
2.9.3
