Add eventlog/trace stuff for capabilities: create/delete/enable/disable

Now that we can adjust the number of capabilities on the fly, we need
this reflected in the eventlog. Previously the eventlog had a single
startup event that declared a static number of capabilities. Obviously
that's no good anymore.

For compatability we're keeping the EVENT_STARTUP but adding new
EVENT_CAP_CREATE/DELETE. The EVENT_CAP_DELETE is actually just the old
EVENT_SHUTDOWN but renamed and extended (using the existing mechanism
to extend eventlog events in a compatible way). So we now emit both
EVENT_STARTUP and EVENT_CAP_CREATE. One day we will drop EVENT_STARTUP.

Since reducing the number of capabilities at runtime does not really
delete them, it just disables them, then we also have new events for
disable/enable.

The old EVENT_SHUTDOWN was in the scheduler class of events. The new
EVENT_CAP_* events are in the unconditional class, along with the
EVENT_CAPSET_* ones. Knowing when capabilities are created and deleted
is crucial to making sense of eventlogs, you always want those events.
In any case, they're extremely low volume.

1 files changed, 4 insertions, 1 deletions

diff --git a/rts/Schedule.c b/rts/Schedule.c
index 7dca76438b..f3ab30b4b4 100644
--- a/rts/Schedule.c
+++ b/rts/Schedule.c
@@ -1985,6 +1985,7 @@ setNumCapabilities (nat new_n_capabilities USED_IF_THREADS)
         //
         for (n = new_n_capabilities; n < enabled_capabilities; n++) {
             capabilities[n].disabled = rtsTrue;
+            traceCapDisable(&capabilities[n]);
         }
         enabled_capabilities = new_n_capabilities;
     }
@@ -1996,6 +1997,7 @@ setNumCapabilities (nat new_n_capabilities USED_IF_THREADS)
         for (n = enabled_capabilities;
              n < new_n_capabilities && n < n_capabilities; n++) {
             capabilities[n].disabled = rtsFalse;
+            traceCapEnable(&capabilities[n]);
         }
         enabled_capabilities = n;
 
@@ -2003,7 +2005,8 @@ setNumCapabilities (nat new_n_capabilities USED_IF_THREADS)
 #if defined(TRACING)
             // Allocate eventlog buffers for the new capabilities.  Note this
             // must be done before calling moreCapabilities(), because that
-            // will emit events to add the new capabilities to capsets.
+            // will emit events about creating the new capabilities and adding
+            // them to existing capsets.
             tracingAddCapapilities(n_capabilities, new_n_capabilities);
 #endif