Replace system block with thread progress block

The ERTS internal system block functionality has been replaced by
new functionality for blocking the system. The old system block
functionality had contention issues and complexity issues. The
new functionality piggy-backs on thread progress tracking functionality
needed by newly introduced lock-free synchronization in the runtime
system. When the functionality for blocking the system isn't used
there is more or less no overhead at all. This since the functionality
for tracking thread progress is there and needed anyway.

1 files changed, 14 insertions, 17 deletions

diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 15e110a6cc..8e8d4cce61 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -52,6 +52,7 @@
 #define ERTS_WANT_GOT_SIGUSR1
 #define WANT_NONBLOCKING    /* must define this to pull in defs from sys.h */
 #include "sys.h"
+#include "erl_thr_progress.h"
 
 #if defined(__APPLE__) && defined(__MACH__) && !defined(__DARWIN__)
 #define __DARWIN__ 1
@@ -2425,11 +2426,7 @@ void erts_do_break_handling(void)
      * therefore, make sure that all threads but this one are blocked before
      * proceeding!
      */
-    erts_smp_block_system(0);
-    /*
-     * NOTE: since we allow gc we are not allowed to lock
-     *       (any) process main locks while blocking system...
-     */
+    erts_smp_thr_progress_block();
 
     /* during break we revert to initial settings */
     /* this is done differently for oldshell */
@@ -2457,7 +2454,7 @@ void erts_do_break_handling(void)
       tcsetattr(0,TCSANOW,&temp_mode);
     }
 
-    erts_smp_release_system();
+    erts_smp_thr_progress_unblock();
 }
 
 /* Fills in the systems representation of the jam/beam process identifier.
@@ -2868,7 +2865,7 @@ erl_sys_schedule(int runnable)
 {
 #ifdef ERTS_SMP
     ERTS_CHK_IO(!runnable);
-    ERTS_SMP_LC_ASSERT(!ERTS_LC_IS_BLOCKING);
+    ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
 #else
     if (runnable) {
 	ERTS_CHK_IO(0);		/* Poll for I/O */
@@ -2937,15 +2934,15 @@ signal_dispatcher_thread_func(void *unused)
 	     *         to other threads.
 	     *
 	     * NOTE 2: The signal dispatcher thread is not a blockable
-	     *         thread (i.e., it hasn't called 
-	     *         erts_register_blockable_thread()). This is
-	     *         intentional. We want to be able to interrupt
-	     *         writing of a crash dump by hitting C-c twice.
-	     *         Since it isn't a blockable thread it is important
-	     *         that it doesn't change the state of any data that
-	     *         a blocking thread expects to have exclusive access
-	     *         to (unless the signal dispatcher itself explicitly
-	     *         is blocking all blockable threads).
+	     *         thread (i.e., not a thread managed by the
+	     *         erl_thr_progress module). This is intentional.
+	     *         We want to be able to interrupt writing of a crash
+	     *         dump by hitting C-c twice. Since it isn't a
+	     *         blockable thread it is important that it doesn't
+	     *         change the state of any data that a blocking thread
+	     *         expects to have exclusive access to (unless the
+	     *         signal dispatcher itself explicitly is blocking all
+	     *         blockable threads).
 	     */
 	    switch (buf[i]) {
 	    case 0: /* Emulator initialized */
@@ -2985,7 +2982,7 @@ signal_dispatcher_thread_func(void *unused)
 			 buf[i]);
 	    }
 	}
-	ERTS_SMP_LC_ASSERT(!ERTS_LC_IS_BLOCKING);
+	ERTS_SMP_LC_ASSERT(!erts_thr_progress_is_blocking());
     }
     return NULL;
 }