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Re: [patch] Change trace buffer size(v2)

Hi All,
Thanks for the review. I am attaching a new version with the changes. How does it look?

On 27/02/13 16:39:07, Pedro Alves wrote:
On 02/18/2013 06:13 PM, Abid, Hafiz wrote:
>
> Hi All, This patch adds support for QTBuffer:size in gdbserver
> and adds commands in gdb to use this packet to change the
> trace buffer size. The default value of the buffer size in
> gdb is -1 which means that target will use whatever size it likes.
>
> I notice that there are some tests that are using "maint packet"
> to send QTBuffer:size. I was not sure what to do with them so
> I have left them alone. If reviewers suggest, I can update/remove them.

Yeah, http://sourceware.org/ml/gdb-patches/2012-02/msg00303.html

So, previously, because gdbserver didn't implement this, some
tests were skipped.  What about after the patch?
I run the circ.exp with it. The qtBuffer:size test work ok. I have to modify circ.exp a little to send literal '-1'. Also I observed that most of the tracing tests in circ.exp were being skipped. I had to add a runto_main before gdb_target_supports_trace to execute those tests. I will send another patch that will take care of circ.exp. 

On 02/18/2013 06:13 PM, Abid, Hafiz wrote:
> +@item QTBuffer:size:@var{size}
> +This packet directs the target to make the trace buffer be of size
> +@var{size} if possible.
> +
Fixed.

This misses explaining the "-1" magic.

> +static int trace_buffer_size;

Should be a ssize_t, or LONGEST.  The latter is probably
better/simpler in this case.
Fixed.


> +init_trace_buffer (int bufsize)

This "int" too.
Fixed. 

xrealloc(NULL, bufsize) is equivalent to xmalloc(bufsize),
so the if is unnecessary.  Write only:

trace_buffer_lo = xrealloc (trace_buffer_lo, bufsize);
Done.

> +static void
> +remote_set_trace_buffer_size (LONGEST val)
> +{
> +  struct remote_state *rs = get_remote_state ();
> +  char *p, *reply;
> +
> +  sprintf (rs->buf, "QTBuffer:size:");
> +  p = rs->buf + strlen (rs->buf);
> +  p += hexnumstr (p, (ULONGEST) val);
> +  putpkt (rs->buf);

This should send -1 really as literal "-1",
instead of ffff..ff, which depends on the size
of ULONGEST, which may not be the same as the target's.
IOW, it's host dependent.
Fixed.


> + reply = remote_get_noisy_reply (&target_buf, &target_buf_size);

We shouldn't be adding more uses of target_buf, target_buf_size.
Use:
  remote_get_noisy_reply (&rs->buf, &rs->buf_size);
Done.

and:

if (*rs->buf == '\0')

but, OTOH, new packets should really be using packet_ok.

This:
looks unrelated to trace buffer size.  Please split it
into a separate patch.
Removed from this patch. Will send in a separate patch.


> +set BUFFER_SIZE 1024
> +gdb_test_no_output "set trace-buffer-size $BUFFER_SIZE" "Set Trace Buffer Size"
> +gdb_test "show trace-buffer-size $BUFFER_SIZE" "Requested size of trace buffer is $BUFFER_SIZE.*" \
> +"Show Trace Buffer Size"
> +

This test doesn't seem to really test that much.  I wonder if
you have ideas on expanding it?
I have tried to expand the test by setting the buffer size to be very small and then testing the buffer to be full.


> +/* This variable is the requested trace buffer size, or -1 to indicate
> + that we don't care and leave it up to the target to set a size. */
> +
> +static int trace_buffer_size = -1;

Should probably be a LONGEST too.  There's to reason to
actually limit to 31-bits, right?

> +  add_setshow_zinteger_cmd ("trace-buffer-size", no_class,
> +			    &trace_buffer_size, _("\

Oh, I see... add_setshow_zinteger_cmd works with int...
Observed that commands added with add_setshow_zinteger_cmd have problem with -1. For var_zinteger, do_set_command uses unsigned int and it ends up comparing 0xffffffff to INT_MAX. If it sounds like an oversight to you then I will send a patch. Here are those lines for a quick look.
unsigned int val;
...
val = parse_and_eval_long (arg);
...
else if (val >= INT_MAX)
error (_("integer %u out of range"), val);


--
Pedro Alves



Following changes were suggested by Yao.
We may mention the new remote packet in NEWS.
Done.

+ error (_("Target does not support setting trace buffer size."));
We may need a warning instead of an error here.
Fixed.

+ void (*to_set_trace_buffer_size) (LONGEST val);
Comments on this field are needed, IMO.
Done.

Also fixed the documentation as suggested by Eli.

Regards,
Abid

2012-03-01  Stan Shebs  <stan@codesourcery.com>
	    Hafiz Abid Qadeer <abidh@codesourcery.com>

	gdb/
	* NEWS: Mention set and show trace-buffer-size commands.
	Mention new packet.
	* target.h (struct target_ops): New method
	to_set_trace_buffer_size.
	(target_set_trace_buffer_size): New macro.
	* target.c (update_current_target): Set up new method.
	* tracepoint.c (trace_buffer_size): New global.
	(start_tracing): Send it to the target.
	(set_trace_buffer_size): New function.
	(_initialize_tracepoint): Add new setshow for trace-buffer-size.
	* remote.c (remote_set_trace_buffer_size): New function.
	(_initialize_remote): Use it.

	gdb/gdbserver/
	* tracepoint.c (trace_buffer_size): New global.
	(init_trace_buffer): Change to one-argument function, add
	realloc option.
	(handle_tracepoint_general_set): Call cmd_bigqtbuffer_size to
	handle QTBuffer:size packet.
	(cmd_bigqtbuffer_size): New function.
	(initialize_tracepoint): Default to a smaller buffer.

gdb/doc/
* gdb.texinfo (Starting and Stopping Trace Experiments): Document
trace-buffer-size set and show commands.
(Tracepoint Packets): Document QTBuffer:size .

	gdb/testsuite/
	* gdb.trace/trace-buffer-size.exp: New file.
	* gdb.trace/trace-buffer-size.c: New file.



diff --git a/gdb/NEWS b/gdb/NEWS
index 0877aa2..8fc433b 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -104,6 +104,10 @@ set debug notification
 show debug notification
   Control display of debugging info for async remote notification.
 
+set trace-buffer-size
+show trace-buffer-size
+  Request target to change the size of trace buffer.
+
 * Removed commands
 
   ** For the Renesas Super-H architecture, the "regs" command has been removed
@@ -159,6 +163,9 @@ show filename-display
   feature to be enabled.  For more information, see:
       http://fedoraproject.org/wiki/Features/MiniDebugInfo
 
+* New remote packets
+  A new packet has been defined to set the trace buffer size.
+
 *** Changes in GDB 7.5
 
 * GDB now supports x32 ABI.  Visit <http://sites.google.com/site/x32abi/>
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 5f39d2e..3cb24d5 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -11728,6 +11728,25 @@ for instance if you are looking at frames from a trace file.
 @end table
 
 @table @code
+@item set trace-buffer-size @var{n}
+@kindex set trace-buffer-size
+Request that the target use a trace buffer of @var{n} bytes.  Not all
+targets will honor the request; they may have a compiled-in size for
+the trace buffer, or some other limitation.  Set to a value of
+@code{-1} to let the target use whatever size it likes.  This is also
+the default.
+
+@item show trace-buffer-size
+@kindex show trace-buffer-size
+Show the current requested size for the trace buffer.  Note that this
+will only match the actual size if the target supports size-setting,
+and was able to handle the requested size.  For instance, if the
+target can only change buffer size between runs, this variable will
+not reflect the change until the next run starts.  Use @code{tstatus}
+to get a report of the actual buffer size.
+@end table
+
+@table @code
 @item set trace-user @var{text}
 @kindex set trace-user
 
@@ -38450,6 +38469,11 @@ available.
 This packet directs the target to use a circular trace buffer if
 @var{value} is 1, or a linear buffer if the value is 0.
 
+@item QTBuffer:size:@var{size}
+This packet directs the target to make the trace buffer be of size
+@var{size} if possible. A value of @code{-1} tells the target to
+use whatever size it likes.
+
 @item QTNotes:@r{[}@var{type}:@var{text}@r{]}@r{[};@var{type}:@var{text}@r{]}@dots{}
 @cindex @samp{QTNotes} packet
 This packet adds optional textual notes to the trace run.  Allowable
diff --git a/gdb/gdbserver/tracepoint.c b/gdb/gdbserver/tracepoint.c
index 0f83ae6..c0b3bd7 100644
--- a/gdb/gdbserver/tracepoint.c
+++ b/gdb/gdbserver/tracepoint.c
@@ -992,6 +992,8 @@ int current_traceframe = -1;
 static int circular_trace_buffer;
 #endif
 
+static LONGEST trace_buffer_size;
+
 /* Pointer to the block of memory that traceframes all go into.  */
 
 static unsigned char *trace_buffer_lo;
@@ -1478,9 +1480,13 @@ clear_inferior_trace_buffer (void)
 #endif
 
 static void
-init_trace_buffer (unsigned char *buf, int bufsize)
+init_trace_buffer (LONGEST bufsize)
 {
-  trace_buffer_lo = buf;
+  trace_buffer_size = bufsize;
+
+  /* If we already have a trace buffer, try realloc'ing.  */
+  trace_buffer_lo = xrealloc (trace_buffer_lo, bufsize);
+
   trace_buffer_hi = trace_buffer_lo + bufsize;
 
   clear_trace_buffer ();
@@ -4020,6 +4026,42 @@ cmd_bigqtbuffer_circular (char *own_buf)
 }
 
 static void
+cmd_bigqtbuffer_size (char *own_buf)
+{
+  ULONGEST val;
+  LONGEST sval;
+  char *packet = own_buf;
+
+  packet += strlen ("QTBuffer:size:");
+
+  /* -1 is sent as literal "-1".  */
+  if (strcmp (packet, "-1") == 0)
+    sval = -1;
+  else
+    {
+      unpack_varlen_hex (packet, &val);
+      sval = (LONGEST)val;
+    }
+  /* If we don't care about the size, or the size is unchanged,
+     all is happy and nothing to do.  */
+  if (sval < 0 || sval == trace_buffer_size)
+    {
+      write_ok (own_buf);
+      return;
+    }
+  /* Right now we can't change the size during a tracing run.  */
+  if (tracing)
+    {
+       write_enn (own_buf);
+       return;
+    }
+  init_trace_buffer (sval);
+  trace_debug ("Trace buffer is now %s bytes",
+                plongest (trace_buffer_size));
+  write_ok (own_buf);
+}
+
+static void
 cmd_qtnotes (char *own_buf)
 {
   size_t nbytes;
@@ -4143,6 +4185,11 @@ handle_tracepoint_general_set (char *packet)
       cmd_bigqtbuffer_circular (packet);
       return 1;
     }
+  else if (strncmp ("QTBuffer:size:", packet, strlen ("QTBuffer:size:")) == 0)
+    {
+      cmd_bigqtbuffer_size (packet);
+      return 1;
+    }
   else if (strncmp ("QTNotes:", packet, strlen ("QTNotes:")) == 0)
     {
       cmd_qtnotes (packet);
@@ -7228,10 +7275,9 @@ get_timestamp (void)
 void
 initialize_tracepoint (void)
 {
-  /* There currently no way to change the buffer size.  */
-  const int sizeOfBuffer = 5 * 1024 * 1024;
-  unsigned char *buf = xmalloc (sizeOfBuffer);
-  init_trace_buffer (buf, sizeOfBuffer);
+  /* Start with a size that's not too large.  */
+  const int sizeOfBuffer = 1024 * 1024;
+  init_trace_buffer (sizeOfBuffer);
 
   /* Wire trace state variable 1 to be the timestamp.  This will be
      uploaded to GDB upon connection and become one of its trace state
diff --git a/gdb/remote.c b/gdb/remote.c
index 88a57c8..8352e80 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -11042,6 +11042,29 @@ remote_get_min_fast_tracepoint_insn_len (void)
     }
 }
 
+static void
+remote_set_trace_buffer_size (LONGEST val)
+{
+  struct remote_state *rs = get_remote_state ();
+  char *reply;
+  char *buf = rs->buf;
+  char *endbuf = rs->buf + get_remote_packet_size ();
+
+  buf += xsnprintf (buf, endbuf - buf, "QTBuffer:size:");
+  /* Send -1 as literal "-1" to avoid host size dependency.  */
+  if (val == -1)
+    buf += xsnprintf (buf, endbuf - buf, "-1");
+  else
+    buf += hexnumstr (buf, (ULONGEST) val);
+
+  putpkt (rs->buf);
+  reply = remote_get_noisy_reply (&rs->buf, &rs->buf_size);
+  if (*rs->buf == '\0')
+    warning (_("Target does not support setting trace buffer size."));
+  if (strcmp (reply, "OK") != 0)
+    warning (_("Bogus reply from target: %s"), reply);
+}
+
 static int
 remote_set_trace_notes (char *user, char *notes, char *stop_notes)
 {
@@ -11219,6 +11242,7 @@ Specify the serial device it is connected to\n\
   remote_ops.to_get_min_fast_tracepoint_insn_len = remote_get_min_fast_tracepoint_insn_len;
   remote_ops.to_set_disconnected_tracing = remote_set_disconnected_tracing;
   remote_ops.to_set_circular_trace_buffer = remote_set_circular_trace_buffer;
+  remote_ops.to_set_trace_buffer_size = remote_set_trace_buffer_size;
   remote_ops.to_set_trace_notes = remote_set_trace_notes;
   remote_ops.to_core_of_thread = remote_core_of_thread;
   remote_ops.to_verify_memory = remote_verify_memory;
diff --git a/gdb/target.c b/gdb/target.c
index 9d8bf6e..2e507e0 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -693,6 +693,7 @@ update_current_target (void)
       INHERIT (to_get_min_fast_tracepoint_insn_len, t);
       INHERIT (to_set_disconnected_tracing, t);
       INHERIT (to_set_circular_trace_buffer, t);
+      INHERIT (to_set_trace_buffer_size, t);
       INHERIT (to_set_trace_notes, t);
       INHERIT (to_get_tib_address, t);
       INHERIT (to_set_permissions, t);
@@ -912,6 +913,9 @@ update_current_target (void)
   de_fault (to_set_circular_trace_buffer,
 	    (void (*) (int))
 	    target_ignore);
+  de_fault (to_set_trace_buffer_size,
+	    (void (*) (LONGEST))
+	    target_ignore);
   de_fault (to_set_trace_notes,
 	    (int (*) (char *, char *, char *))
 	    return_zero);
diff --git a/gdb/target.h b/gdb/target.h
index 1971265..c99642d 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -806,6 +806,8 @@ struct target_ops
        disconnection - set VAL to 1 to keep tracing, 0 to stop.  */
     void (*to_set_disconnected_tracing) (int val);
     void (*to_set_circular_trace_buffer) (int val);
+    /* Set the size of trace buffer in the target.  */
+    void (*to_set_trace_buffer_size) (LONGEST val);
 
     /* Add/change textual notes about the trace run, returning 1 if
        successful, 0 otherwise.  */
@@ -1700,6 +1702,9 @@ extern char *target_fileio_read_stralloc (const char *filename);
 #define	target_set_circular_trace_buffer(val)	\
   (*current_target.to_set_circular_trace_buffer) (val)
 
+#define	target_set_trace_buffer_size(val)	\
+  (*current_target.to_set_trace_buffer_size) (val)
+
 #define	target_set_trace_notes(user,notes,stopnotes)		\
   (*current_target.to_set_trace_notes) ((user), (notes), (stopnotes))
 
diff --git a/gdb/testsuite/gdb.trace/trace-buffer-size.c b/gdb/testsuite/gdb.trace/trace-buffer-size.c
new file mode 100644
index 0000000..e32b756
--- /dev/null
+++ b/gdb/testsuite/gdb.trace/trace-buffer-size.c
@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011-2013 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+int var = 10;
+
+int
+test_function ()
+{
+  return 0;
+}
+
+int
+main ()
+{
+  test_function (); 
+  return 0; /*breakpoint1*/
+}
diff --git a/gdb/testsuite/gdb.trace/trace-buffer-size.exp b/gdb/testsuite/gdb.trace/trace-buffer-size.exp
new file mode 100644
index 0000000..4533f77
--- /dev/null
+++ b/gdb/testsuite/gdb.trace/trace-buffer-size.exp
@@ -0,0 +1,54 @@
+# Copyright 1998-2013 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib "trace-support.exp"
+
+standard_testfile
+
+if [prepare_for_testing ${testfile}.exp $testfile $srcfile \
+        {debug nowarnings}] {
+    untested "failed to prepare for trace tests"
+    return -1
+}
+
+if ![runto_main] {
+    fail "can't run to main to check for trace support"
+    return -1
+}
+
+if ![gdb_target_supports_trace] {
+    unsupported "target does not support trace"
+    return -1;
+}
+
+set BUFFER_SIZE 4
+gdb_test_no_output "set trace-buffer-size $BUFFER_SIZE" "Set Trace Buffer Size"
+gdb_test "show trace-buffer-size $BUFFER_SIZE" "Requested size of trace buffer is $BUFFER_SIZE.*" \
+"Show Trace Buffer Size"
+
+# We set trace buffer to very small size. Then after running trace, we check
+# if it is full. This will show if setting trace buffer size really worked.
+gdb_breakpoint ${srcfile}:[gdb_get_line_number "breakpoint1"]
+gdb_test "trace test_function" \
+    "Tracepoint \[0-9\]+ at .*" \
+    "set tracepoint at test_function"
+gdb_trace_setactions "1. Set action for trace point" "" \
+    "collect var" "^$"
+gdb_test "tstart"     ".*" ""
+gdb_test "continue"   ".*" ""
+gdb_test "tstatus"    ".*Trace stopped because the buffer was full.*" \
+"Buffer full check"
+gdb_test "tstop"    ".*" ""
+
diff --git a/gdb/tracepoint.c b/gdb/tracepoint.c
index 9a80aa3..bd4f2c7 100644
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -173,6 +173,11 @@ static int disconnected_tracing;
 
 static int circular_trace_buffer;
 
+/* This variable is the requested trace buffer size, or -1 to indicate
+   that we don't care and leave it up to the target to set a size.  */
+
+static int trace_buffer_size = -1;
+
 /* Textual notes applying to the current and/or future trace runs.  */
 
 char *trace_user = NULL;
@@ -1829,6 +1834,7 @@ start_tracing (char *notes)
   /* Set some mode flags.  */
   target_set_disconnected_tracing (disconnected_tracing);
   target_set_circular_trace_buffer (circular_trace_buffer);
+  target_set_trace_buffer_size (trace_buffer_size);
 
   if (!notes)
     notes = trace_notes;
@@ -3231,6 +3237,13 @@ set_circular_trace_buffer (char *args, int from_tty,
 }
 
 static void
+set_trace_buffer_size (char *args, int from_tty,
+			   struct cmd_list_element *c)
+{
+  target_set_trace_buffer_size (trace_buffer_size);
+}
+
+static void
 set_trace_user (char *args, int from_tty,
 		struct cmd_list_element *c)
 {
@@ -5416,6 +5429,16 @@ up and stopping the trace run."),
 			   &setlist,
 			   &showlist);
 
+  add_setshow_zinteger_cmd ("trace-buffer-size", no_class,
+			    &trace_buffer_size, _("\
+Set requested size of trace buffer."), _("\
+Show requested size of trace buffer."), _("\
+Use this to choose a size for the trace buffer.  Some targets\n\
+may have fixed or limited buffer sizes.  A value of -1 disables\n\
+any attempt to set the buffer size and lets the target choose."),
+			    set_trace_buffer_size, NULL,
+			    &setlist, &showlist);
+
   add_setshow_string_cmd ("trace-user", class_trace,
 			  &trace_user, _("\
 Set the user name to use for current and future trace runs"), _("\
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