diff options
| author | Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com> | 2017-04-24 14:19:58 -0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-05-05 12:09:59 +0200 |
| commit | 31f5a726b59bda5580e2f9413867893501dd7d93 (patch) | |
| tree | 33c91bb25066d13fc9f79aae3ca2379465dcbe51 /util/trace-events | |
| parent | f68826989cd4d1217797251339579c57b3c0934e (diff) | |
trace: add qemu mutex lock and unlock trace events
These trace events were very useful to help me to understand and find a
reordering issue in vfio, for example:
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc0, 0x2020c, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc4, 0xa0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
that also helped me to see the desired result after the fix:
qemu_mutex_lock locked mutex 0x10905ad8
vfio_region_write (0001:03:00.0:region1+0xc0, 0x2000c, 4)
vfio_region_write (0001:03:00.0:region1+0xc4, 0xb0000, 4)
qemu_mutex_unlock unlocked mutex 0x10905ad8
So it could be a good idea to have these traces implemented. It's worth
mentioning that they should be surgically enabled during the debugging,
otherwise it can flood the trace logs with lock/unlock messages.
How to use it:
trace-event qemu_mutex_lock on|off
trace-event qemu_mutex_unlock on|off
or
trace-event qemu_mutex* on|off
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Message-Id: <1493054398-26013-1-git-send-email-joserz@linux.vnet.ibm.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
[Also handle trylock, cond_wait and win32; trace "unlocked" while still
in the critical section, so that "unlocked" always comes before the
next "locked" tracepoint. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'util/trace-events')
| -rw-r--r-- | util/trace-events | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/util/trace-events b/util/trace-events index b44ef4f895..fa540c620b 100644 --- a/util/trace-events +++ b/util/trace-events @@ -55,3 +55,7 @@ lockcnt_futex_wait_prepare(const void *lockcnt, int expected, int new) "lockcnt lockcnt_futex_wait(const void *lockcnt, int val) "lockcnt %p waiting on %d" lockcnt_futex_wait_resume(const void *lockcnt, int new) "lockcnt %p after wait: %d" lockcnt_futex_wake(const void *lockcnt) "lockcnt %p waking up one waiter" + +# util/qemu-thread-posix.c +qemu_mutex_locked(void *lock) "locked mutex %p" +qemu_mutex_unlocked(void *lock) "unlocked mutex %p" |