xentrace updates

diff -r 859a372efa66 -r 16ef34de0129 tools/xentrace/xentrace.c
@@ -149,6 +149,7 @@
 {
     struct cpu_change_record *rec;
     long need_to_consume, free, freed;
+    int last_cpu = -1;
 
     if ( membuf.pending_size > 0 )
     {

@@ -193,11 +194,25 @@
 
         if ( need_to_consume > 0 )
         {
+            last_cpu = rec->data.cpu;
             MEMBUF_CONS_INCREMENT(freed);
             need_to_consume -= freed;
         }
     } while( need_to_consume > 0 );
 
+    /* For good tsc consistency, we need to start at a low-cpu buffer.  Keep
+     * skipping until the cpu goes down or stays the same. */
+    rec = (struct cpu_change_record *)MEMBUF_POINTER(membuf.cons);
+    while ( rec->data.cpu > last_cpu )
+    {
+        last_cpu = rec->data.cpu; 
+
+        freed = sizeof(*rec) + rec->data.window_size;
+        
+        MEMBUF_CONS_INCREMENT(freed);
+        rec = (struct cpu_change_record *)MEMBUF_POINTER(membuf.cons);
+    }
+
 start_window:
     /*
      * Start writing "pending" data.  Update prod once all this data is

diff -r 16ef34de0129 -r ce0812566a4d tools/xentrace/xentrace.c
@@ -58,7 +58,8 @@
     unsigned long timeout;
     unsigned long memory_buffer;
     uint8_t discard:1,
-        disable_tracing:1;
+        disable_tracing:1,
+        start_disabled:1;
 } settings_t;
 
 struct t_struct {

@@ -659,6 +660,10 @@
 
     /* setup access to trace buffers */
     get_tbufs(&tbufs_mfn, &tinfo_size);
+
+    if ( opts.start_disabled )
+        disable_tbufs();
+    
     tbufs = map_tbufs(tbufs_mfn, num, tinfo_size);
 
     size = tbufs->t_info->tbuf_size * XC_PAGE_SIZE;

@@ -791,6 +796,9 @@
 "                          it exits. Selecting this option will tell it to\n" \
 "                          keep tracing on.  Traces will be collected in\n" \
 "                          Xen's trace buffers until they become full.\n" \
+"  -X  --start-disabled    Setup trace buffers and listen, but don't enable\n" \
+"                          tracing. (Useful if tracing will be enabled by\n" \
+"                          else.)\n" \
 "  -T  --time-interval=s   Run xentrace for s seconds and quit.\n" \
 "  -?, --help              Show this message\n" \
 "  -V, --version           Print program version\n" \

@@ -914,12 +922,13 @@
         { "memory-buffer",  required_argument, 0, 'M' },
         { "discard-buffers", no_argument,      0, 'D' },
         { "dont-disable-tracing", no_argument, 0, 'x' },
+        { "start-disabled", no_argument,       0, 'X' },
         { "help",           no_argument,       0, '?' },
         { "version",        no_argument,       0, 'V' },
         { 0, 0, 0, 0 }
     };
 
-    while ( (option = getopt_long(argc, argv, "t:s:c:e:S:r:T:M:Dx?V",
+    while ( (option = getopt_long(argc, argv, "t:s:c:e:S:r:T:M:DxX?V",
                     long_options, NULL)) != -1) 
     {
         switch ( option )

@@ -957,6 +966,10 @@
             opts.disable_tracing = 0;
             break;
 
+        case 'X': /* Start disabled */
+            opts.start_disabled = 1;
+            break;
+
         case 'T':
             opts.timeout = argtol(optarg, 0);
             break;

@@ -993,6 +1006,7 @@
     opts.cpu_mask = 0;
     opts.disk_rsvd = 0;
     opts.disable_tracing = 1;
+    opts.start_disabled = 0;
     opts.timeout = 0;
 
     parse_args(argc, argv);

diff -r ce0812566a4d -r a0d521070853 tools/xentrace/xentrace.c
@@ -804,6 +804,9 @@
 "  -V, --version           Print program version\n" \
 "  -M, --memory-buffer=b   Copy trace records to a circular memory buffer.\n" \
 "                          Dump to file on exit.\n" \
+"  -r  --reserve-disk-space=n Before writing trace records to disk, check to see\n" \
+"                          that after the write there will be at least n space\n" \
+"                          left on the disk.\n" \
 "\n" \
 "This tool is used to capture trace buffer data from Xen. The\n" \
 "data is output in a binary format, in the following order:\n" \