[m-dev.] Please help... once more

[Erwan Jahier]

Fergus,

I have benchmarked the Morphine/collect command on big execution traces. Here
are (roughly) the overhead I get:

with 10 000 evts there is no overhead, 
with 100 000 evts, there is a small overhead, 
...
with 2 000 000 evts, there is an overhead factor of 120, 
with 4 000 000 evts, there is an overhead factor of 230,
...

Then it seems to stabilize; with 200 000 000 events, it still have a factor
that is around 230: so at least there is a good news... )-;

I can see several reasons to that:
(1) filter is called after a long series of branches (swithes and if-then-else)
(2) filter is called after a long series functions calls: MR_trace ->
MR_trace_real -> MR_trace_event -> MR_trace_event_external.
(3) During while, a certain number of calls to functions that save and restore
registers, heaps, etc. are made to collect probably don't need:
   - restore_transient_registers(),
   - save__transient_registers(), 
   - MR_saved_global_hp(saved_regs), 
   - MR_copy_saved_regs_to_regs(), 
   - ...

So I decided to try to put the call to filter in MR_trace_real() to see what
happens (it is also a good step to make collect available from mdb BTW).
So what I have added in mercury_trace.c:MR_trace_real() looks like that (+ 
boring changes to make some symbols available from mercury_trace.c):

        
@@ -135,29 +132,6 @@
        #endif	/* MR_TRACE_HISTOGRAM */

+    switch (MR_trace_ctrl.MR_trace_cmd) {
+	case MR_CMD_COLLECT:
+             port = (MR_Trace_Port) layout->MR_sll_port;
+	      path = layout->MR_sll_entry->MR_sle_module_layout
+		    ->MR_ml_string_table + layout->MR_sll_goal_path;
+	      MR_COLLECT_filter(seqno, depth, port, layout, 
+                   path, &stop_collecting);
+	      if (stop_collecting) {
+		MR_send_collect_result();
+		MR_send_message_to_socket("execution_continuing");
+		}
+		return NULL;	
+	  
	case MR_CMD_FINISH:
         ...


Unfortunately, I run into a Bus error (I was expecting something like that,
actually...). 

I guess there are registers, or heaps, or whatever, that should be saved or 
restored, or ....

I am a bit confused about the magic incantations I should use to make it working.
Could someone (Well, I guess Fergus once more) help me?

Just in case that helps you, here is my current gdb session. 

==============================================================================
GNU gdb 4.17
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GDB is free software, covered by the GNU General Public License, and you are
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Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "sparc-sun-solaris2.4"...
(gdb) b MR_COLLECT_filter
Breakpoint 1 at 0x52960: file mercury_trace_external.c, line 1486.
(gdb) r
Starting program: /home/terre/d02/lande/jahier/these/./queens

Breakpoint 1, MR_COLLECT_filter (seqno=0, depth=4290683468, port=1356800, 
    layout=0x1520d8, path=0x16 <Address 0x16 out of bounds>, 
    stop_collecting=0xff1c84c0 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) c
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=0, depth=0, port=MR_PORT_CALL, 
    layout=0x1, path=0x0, stop_collecting=0x0) at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=2, depth=2, port=4280006636, 
    layout=0xffbeb407, path=0x2 <Address 0x2 out of bounds>, 
    stop_collecting=0xff1c8f58 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=2, depth=2, port=4280006636, 
    layout=0xffbeb407, path=0x2 <Address 0x2 out of bounds>, 
    stop_collecting=0xff1c8f58 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=3, depth=2, port=4280006636, 
    layout=0xffbeb407, path=0x2 <Address 0x2 out of bounds>, 
    stop_collecting=0xff1c8f58 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=4, depth=3, port=4280006636, 
    layout=0xffbeb407, path=0x3 <Address 0x3 out of bounds>, 
    stop_collecting=0xff1c8f58 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Breakpoint 1, MR_COLLECT_filter (seqno=4, depth=3, port=4280006636, 
    layout=0xffbeb407, path=0x3 <Address 0x3 out of bounds>, 
    stop_collecting=0xff1c8f58 "") at mercury_trace_external.c:1486
1486            if (MR_collect_arguments) {
(gdb) 
Continuing.

Program received signal SIGBUS, Bus error.
0x4e754 in _entry_mercury__queens__qdelete_3_0 () at queens.c:3455
3455            if (((Integer) r2 != (Integer) MR_mkword(MR_mktag(0), (Word *) MR_mkbody((Integer) 0))))

(gdb) bt
#0  0x4e754 in _entry_mercury__queens__qdelete_3_0 () at queens.c:3455
#1  0x105130 in MR_call_engine (entry_point=0x10cc38, 
    catch_exceptions=0 '\000') at mercury_engine.c:338
#2  0x10cafc in mercury_runtime_main () at mercury_wrapper.c:932
#3  0x4d618 in mercury_call_main () at queens_init.c:317
#4  0x4d650 in mercury_main (argc=1, argv=0xffbef064) at queens_init.c:331
#5  0x4d670 in main (argc=1, argv=0xffbef064) at queens_init.c:341


-- 
R1.


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