record-btrace: add bts buffer size configuration option

Allow the size of the branch trace ring buffer to be defined by the
user.  The specified buffer size will be used when BTS tracing is
enabled for new threads.

The obtained buffer size may differ from the requested size.  The
actual buffer size for the current thread is shown in the "info record"
command.

Bigger buffers mean longer traces, but also longer processing time.

2015-02-09  Markus Metzger  <markus.t.metzger@intel.com>

	* btrace.c (parse_xml_btrace_conf_bts): Add size.
	(btrace_conf_bts_attributes): New.
	(btrace_conf_children): Add attributes.
	* common/btrace-common.h (btrace_config_bts): New.
	(btrace_config)<bts>: New.
	(btrace_config): Update comment.
	* nat/linux-btrace.c (linux_enable_btrace, linux_enable_bts):
	Use config.
	* features/btrace-conf.dtd: Increment version.  Add size
	attribute to bts element.
	* record-btrace.c (set_record_btrace_bts_cmdlist,
	show_record_btrace_bts_cmdlist): New.
	(record_btrace_adjust_size, record_btrace_print_bts_conf,
	record_btrace_print_conf, cmd_set_record_btrace_bts,
	cmd_show_record_btrace_bts): New.
	(record_btrace_info): Call record_btrace_print_conf.
	(_initialize_record_btrace): Add commands.
	* remote.c: Add PACKET_Qbtrace_conf_bts_size enum.
	(remote_protocol_features): Add Qbtrace-conf:bts:size packet.
	(btrace_sync_conf): Synchronize bts size.
	(_initialize_remote): Add Qbtrace-conf:bts:size packet.
	* NEWS: Announce new commands and new packets.

doc/
	* gdb.texinfo (Branch Trace Configuration Format): Add size.
	(Process Record and Replay): Describe new set|show commands.
	(General Query Packets): Describe Qbtrace-conf:bts:size packet.

testsuite/
	* gdb.btrace/buffer-size: New.

gdbserver/
	* linux-low.c (linux_low_btrace_conf): Print size.
	* server.c (handle_btrace_conf_general_set): New.
	(hanle_general_set): Call handle_btrace_conf_general_set.
	(handle_query): Report Qbtrace-conf:bts:size as supported.

1 files changed, 14 insertions, 0 deletions

diff --git a/gdb/NEWS b/gdb/NEWS
index b3f8f60..624f508 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -41,6 +41,12 @@ maint set symbol-cache-size
 maint show symbol-cache-size
   Control the size of the symbol cache.
 
+set|show record btrace bts buffer-size
+  Set and show the size of the ring buffer used for branch tracing in
+  BTS format.
+  The obtained size may differ from the requested size.  Use "info
+  record" to see the obtained buffer size.
+
 * The command 'thread apply all' can now support new option '-ascending'
   to call its specified command for all threads in ascending order.
 
@@ -54,6 +60,14 @@ maint show symbol-cache-size
 qXfer:btrace-conf:read
   Return the branch trace configuration for the current thread.
 
+Qbtrace-conf:bts:size
+  Set the requested ring buffer size for branch tracing in BTS format.
+
+* The info record command now shows the recording format and the
+  branch tracing configuration for the current thread when using
+  the btrace record target.
+  For the BTS format, it shows the ring buffer size.
+
 *** Changes in GDB 7.9
 
 * GDB now supports hardware watchpoints on x86 GNU Hurd.