Add wait_event_timing: Oracle-style wait event instrumentation

configure.ac

@@ -225,6 +225,14 @@ fi
 AC_SUBST(DTRACEFLAGS)])
 AC_SUBST(enable_dtrace)
 
+#
+# --enable-wait-event-timing adds wait event timing instrumentation
+#
+PGAC_ARG_BOOL(enable, wait-event-timing, no,
+              [build with wait event timing instrumentation],
+              [AC_DEFINE([USE_WAIT_EVENT_TIMING], 1,
+                         [Define to 1 to build with wait event timing. (--enable-wait-event-timing)])])
+
 #
 # TAP tests
 #

meson.build

@@ -505,6 +505,7 @@ meson_bin = find_program(meson_binpath, native: true)
 
 cdata.set('USE_ASSERT_CHECKING', get_option('cassert') ? 1 : false)
 cdata.set('USE_INJECTION_POINTS', get_option('injection_points') ? 1 : false)
+cdata.set('USE_WAIT_EVENT_TIMING', get_option('wait_event_timing') ? 1 : false)
 
 blocksize = get_option('blocksize').to_int() * 1024
 

meson_options.txt

@@ -40,6 +40,9 @@ option('pgport', type: 'integer', value: 5432,
 option('cassert', type: 'boolean', value: false,
   description: 'Enable assertion checks (for debugging)')
 
+option('wait_event_timing', type: 'boolean', value: false,
+  description: 'Enable wait event timing instrumentation')
+
 option('tap_tests', type: 'feature', value: 'auto',
   description: 'Enable TAP tests')
 

src/backend/storage/ipc/ipci.c

@@ -137,6 +137,11 @@ CalculateShmemSize(void)
 	size = add_size(size, AsyncShmemSize());
 	size = add_size(size, StatsShmemSize());
 	size = add_size(size, WaitEventCustomShmemSize());
+#ifdef USE_WAIT_EVENT_TIMING
+	size = add_size(size, WaitEventTimingShmemSize());
+	size = add_size(size, WaitEventQueryShmemSize());
+	size = add_size(size, WaitEventTraceShmemSize());
+#endif
 	size = add_size(size, InjectionPointShmemSize());
 	size = add_size(size, SlotSyncShmemSize());
 	size = add_size(size, AioShmemSize());
@@ -325,6 +330,11 @@ CreateOrAttachShmemStructs(void)
 	AsyncShmemInit();
 	StatsShmemInit();
 	WaitEventCustomShmemInit();
+#ifdef USE_WAIT_EVENT_TIMING
+	WaitEventTimingShmemInit();
+	WaitEventQueryShmemInit();
+	WaitEventTraceShmemInit();
+#endif
 	InjectionPointShmemInit();
 	AioShmemInit();
 	WaitLSNShmemInit();

src/backend/storage/lmgr/proc.c

@@ -529,6 +529,9 @@ InitProcess(void)
 
 	/* now that we have a proc, report wait events to shared memory */
 	pgstat_set_wait_event_storage(&MyProc->wait_event_info);
+#ifdef USE_WAIT_EVENT_TIMING
+	pgstat_set_wait_event_timing_storage(GetNumberFromPGProc(MyProc));
+#endif
 
 	/*
 	 * We might be reusing a semaphore that belonged to a failed process. So
@@ -701,6 +704,9 @@ InitAuxiliaryProcess(void)
 
 	/* now that we have a proc, report wait events to shared memory */
 	pgstat_set_wait_event_storage(&MyProc->wait_event_info);
+#ifdef USE_WAIT_EVENT_TIMING
+	pgstat_set_wait_event_timing_storage(GetNumberFromPGProc(MyProc));
+#endif
 
 	/* Check that group locking fields are in a proper initial state. */
 	Assert(MyProc->lockGroupLeader == NULL);
@@ -991,6 +997,9 @@ ProcKill(int code, Datum arg)
 	 */
 	SwitchBackToLocalLatch();
 	pgstat_reset_wait_event_storage();
+#ifdef USE_WAIT_EVENT_TIMING
+	pgstat_reset_wait_event_timing_storage();
+#endif
 
 	proc = MyProc;
 	MyProc = NULL;
@@ -1056,6 +1065,9 @@ AuxiliaryProcKill(int code, Datum arg)
 	/* look at the equivalent ProcKill() code for comments */
 	SwitchBackToLocalLatch();
 	pgstat_reset_wait_event_storage();
+#ifdef USE_WAIT_EVENT_TIMING
+	pgstat_reset_wait_event_timing_storage();
+#endif
 
 	proc = MyProc;
 	MyProc = NULL;

src/backend/utils/activity/Makefile

@@ -34,7 +34,8 @@ OBJS = \
 	pgstat_wal.o \
 	pgstat_xact.o \
 	wait_event.o \
-	wait_event_funcs.o
+	wait_event_funcs.o \
+	wait_event_timing.o
 
 # Force these dependencies to be known even without dependency info built:
 wait_event.o: wait_event.c $(top_builddir)/src/backend/utils/pgstat_wait_event.c

src/backend/utils/activity/backend_status.c

@@ -20,6 +20,9 @@
 #include "storage/proc.h"		/* for MyProc */
 #include "storage/procarray.h"
 #include "utils/ascii.h"
+#ifdef USE_WAIT_EVENT_TIMING
+#include "utils/wait_event_timing.h"
+#endif
 #include "utils/guc.h"			/* for application_name */
 #include "utils/memutils.h"
 
@@ -249,6 +252,15 @@ pgstat_beinit(void)
 	Assert(MyProcNumber >= 0 && MyProcNumber < NumBackendStatSlots);
 	MyBEEntry = &BackendStatusArray[MyProcNumber];
 
+#ifdef USE_WAIT_EVENT_TIMING
+	/*
+	 * Point the wait event timing query_id pointer at our st_query_id.
+	 * This must happen here (not in InitProcess) because MyBEEntry is
+	 * not yet set when pgstat_set_wait_event_timing_storage() runs.
+	 */
+	my_wait_event_query_id_ptr = &MyBEEntry->st_query_id;
+#endif
+
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
 }

src/backend/utils/activity/meson.build

@@ -18,6 +18,7 @@ backend_sources += files(
   'pgstat_subscription.c',
   'pgstat_wal.c',
   'pgstat_xact.c',
+  'wait_event_timing.c',
 )
 
 # this includes a .c file with contents generated in ../../../include/activity,