qsp: track BQL callers explicitly

The BQL is acquired via qemu_mutex_lock_iothread(), which makes
the profiler assign the associated wait time (i.e. most of
BQL wait time) entirely to that function. This loses the original
call site information, which does not help diagnose BQL contention.
Fix it by tracking the callers explicitly.

Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/util/qsp.c b/util/qsp.c
index 4dc851e456..b0c2575d10 100644
--- a/util/qsp.c
+++ b/util/qsp.c
@@ -65,6 +65,7 @@
 
 enum QSPType {
     QSP_MUTEX,
+    QSP_BQL_MUTEX,
     QSP_REC_MUTEX,
     QSP_CONDVAR,
 };
@@ -123,10 +124,12 @@ static bool qsp_initialized, qsp_initializing;
 
 static const char * const qsp_typenames[] = {
     [QSP_MUTEX]     = "mutex",
+    [QSP_BQL_MUTEX] = "BQL mutex",
     [QSP_REC_MUTEX] = "rec_mutex",
     [QSP_CONDVAR]   = "condvar",
 };
 
+QemuMutexLockFunc qemu_bql_mutex_lock_func = qemu_mutex_lock_impl;
 QemuMutexLockFunc qemu_mutex_lock_func = qemu_mutex_lock_impl;
 QemuMutexTrylockFunc qemu_mutex_trylock_func = qemu_mutex_trylock_impl;
 QemuRecMutexLockFunc qemu_rec_mutex_lock_func = qemu_rec_mutex_lock_impl;
@@ -419,6 +422,7 @@ static inline void qsp_entry_record(QSPEntry *e, int64_t delta)
         return err;                                                     \
     }
 
+QSP_GEN_VOID(QemuMutex, QSP_BQL_MUTEX, qsp_bql_mutex_lock, qemu_mutex_lock_impl)
 QSP_GEN_VOID(QemuMutex, QSP_MUTEX, qsp_mutex_lock, qemu_mutex_lock_impl)
 QSP_GEN_RET1(QemuMutex, QSP_MUTEX, qsp_mutex_trylock, qemu_mutex_trylock_impl)
 
@@ -453,6 +457,7 @@ void qsp_enable(void)
 {
     atomic_set(&qemu_mutex_lock_func, qsp_mutex_lock);
     atomic_set(&qemu_mutex_trylock_func, qsp_mutex_trylock);
+    atomic_set(&qemu_bql_mutex_lock_func, qsp_bql_mutex_lock);
     atomic_set(&qemu_rec_mutex_lock_func, qsp_rec_mutex_lock);
     atomic_set(&qemu_rec_mutex_trylock_func, qsp_rec_mutex_trylock);
     atomic_set(&qemu_cond_wait_func, qsp_cond_wait);
@@ -462,6 +467,7 @@ void qsp_disable(void)
 {
     atomic_set(&qemu_mutex_lock_func, qemu_mutex_lock_impl);
     atomic_set(&qemu_mutex_trylock_func, qemu_mutex_trylock_impl);
+    atomic_set(&qemu_bql_mutex_lock_func, qemu_mutex_lock_impl);
     atomic_set(&qemu_rec_mutex_lock_func, qemu_rec_mutex_lock_impl);
     atomic_set(&qemu_rec_mutex_trylock_func, qemu_rec_mutex_trylock_impl);
     atomic_set(&qemu_cond_wait_func, qemu_cond_wait_impl);