diff options
| author | Wei Huang <wei@redhat.com> | 2015-01-21 16:15:31 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-01-26 12:27:05 +0100 |
| commit | 874b1cfad51e325d535f99261f91c92df444c18c (patch) | |
| tree | b8f1088e836d817c83889fa3cd10ef8316f9d850 /scripts/kvm | |
| parent | 2c9d535a2e43699de32987b76cf548a39e4d04d2 (diff) | |
| download | qemu-874b1cfad51e325d535f99261f91c92df444c18c.tar.gz | |
kvm_stat: Print errno when syscall to perf_event_open() fails
kvm_stat uses syscall() to call perf_event_open(). If this function
call fails, the returned value is -1, which doesn't tell the details
of such failure (i.e. ENOSYS or EINVAL). This patch retrieves errno
and prints it when syscall() fails. The error message will look like
"Exception: perf_event_open failed, errno = 38".
Signed-off-by: Wei Huang <wei@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'scripts/kvm')
| -rwxr-xr-x | scripts/kvm/kvm_stat | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/scripts/kvm/kvm_stat b/scripts/kvm/kvm_stat index 95c650b1c3..8f6f00715e 100755 --- a/scripts/kvm/kvm_stat +++ b/scripts/kvm/kvm_stat @@ -13,6 +13,7 @@ import curses import sys, os, time, optparse, ctypes +from ctypes import * class DebugfsProvider(object): def __init__(self): @@ -247,6 +248,9 @@ import struct, array libc = ctypes.CDLL('libc.so.6') syscall = libc.syscall +get_errno = libc.__errno_location +get_errno.restype = POINTER(c_int) + class perf_event_attr(ctypes.Structure): _fields_ = [('type', ctypes.c_uint32), ('size', ctypes.c_uint32), @@ -330,7 +334,8 @@ class Event(object): group_leader = group.events[0].fd fd = _perf_event_open(attr, -1, group.cpu, group_leader, 0) if fd == -1: - raise Exception('perf_event_open failed') + err = get_errno()[0] + raise Exception('perf_event_open failed, errno = ' + err.__str__()) if filter: import fcntl fcntl.ioctl(fd, ioctl_numbers['SET_FILTER'], filter) |