1 files changed, 57 insertions, 3 deletions

diff --git a/rts/RtsFlags.c b/rts/RtsFlags.c
index 24181d32b0..fcc1f49a36 100644
--- a/rts/RtsFlags.c
+++ b/rts/RtsFlags.c
@@ -163,6 +163,9 @@ void initRtsFlagsDefaults(void)
     RtsFlags.TraceFlags.tracing       = TRACE_NONE;
     RtsFlags.TraceFlags.timestamp     = rtsFalse;
     RtsFlags.TraceFlags.scheduler     = rtsFalse;
+    RtsFlags.TraceFlags.gc            = rtsFalse;
+    RtsFlags.TraceFlags.sparks_sampled= rtsFalse;
+    RtsFlags.TraceFlags.sparks_full   = rtsFalse;
 #endif
 
     RtsFlags.MiscFlags.tickInterval	= 20;  /* In milliseconds */
@@ -288,9 +291,15 @@ usage_text[] = {
 #  endif
 "             where [flags] can contain:",
 "                s    scheduler events",
+"                g    GC events",
+"                p    par spark events (sampled)",
+"                f    par spark events (full detail)",
 #  ifdef DEBUG
 "                t    add time stamps (only useful with -v)",
 #  endif
+"                a    all event classes above",
+"               -x    disable an event class, for any flag above",
+"             the initial enabled event classes are 'sgp'",
 #endif
 
 #if !defined(PROFILING)
@@ -1429,19 +1438,64 @@ decodeSize(const char *flag, nat offset, StgWord64 min, StgWord64 max)
 static void read_trace_flags(char *arg)
 {
     char *c;
+    rtsBool enabled = rtsTrue;
+    /* Syntax for tracing flags currently looks like:
+     *
+     *   -l    To turn on eventlog tracing with default trace classes
+     *   -lx   Turn on class 'x' (for some class listed below)
+     *   -l-x  Turn off class 'x'
+     *   -la   Turn on all classes
+     *   -l-a  Turn off all classes
+     *
+     * This lets users say things like:
+     *   -la-p    "all but sparks"
+     *   -l-ap    "only sparks"
+     */
+
+    /* Start by turning on the default tracing flags.
+     *
+     * Currently this is all the trace classes, except full-detail sparks.
+     * Similarly, in future we might default to slightly less verbose
+     * scheduler or GC tracing.
+     */
+    RtsFlags.TraceFlags.scheduler      = rtsTrue;
+    RtsFlags.TraceFlags.gc             = rtsTrue;
+    RtsFlags.TraceFlags.sparks_sampled = rtsTrue;
 
     for (c  = arg; *c != '\0'; c++) {
         switch(*c) {
         case '\0':
             break;
+        case '-':
+            enabled = rtsFalse;
+            break;
+        case 'a':
+            RtsFlags.TraceFlags.scheduler      = enabled;
+            RtsFlags.TraceFlags.gc             = enabled;
+            RtsFlags.TraceFlags.sparks_sampled = enabled;
+            RtsFlags.TraceFlags.sparks_full    = enabled;
+            enabled = rtsTrue;
+            break;
+
         case 's':
-            RtsFlags.TraceFlags.scheduler = rtsTrue;
+            RtsFlags.TraceFlags.scheduler = enabled;
+            enabled = rtsTrue;
+            break;
+        case 'p':
+            RtsFlags.TraceFlags.sparks_sampled = enabled;
+            enabled = rtsTrue;
+            break;
+        case 'f':
+            RtsFlags.TraceFlags.sparks_full = enabled;
+            enabled = rtsTrue;
             break;
         case 't':
-            RtsFlags.TraceFlags.timestamp = rtsTrue;
+            RtsFlags.TraceFlags.timestamp = enabled;
+            enabled = rtsTrue;
             break;
         case 'g':
-            // ignored for backwards-compat
+            RtsFlags.TraceFlags.gc        = enabled;
+            enabled = rtsTrue;
             break;
         default:
             errorBelch("unknown trace option: %c",*c);