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Reduce Hg packet (select remote general thread) bouncing

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A patch I wrote made GDB pull the thread list sooner when debugging
with target remote, and I noticed an intended consequence.  GDB
started bouncing around the currently selected remote/general thread
more frequently.  E.g.:

  Sending packet: $qTMinFTPILen#3b...Packet received: 5
 +Sending packet: $Hgp726d.726d#53...Packet received: OK
  Sending packet: $m400680,40#2f...Packet received: 85c0741455bff00d60004889e5ffd05de97bffffff0f1f00e973ffffff0f1f00554889e5c745fc00000000c745fc01000000e900000000c745fc02000000b800
 +Sending packet: $Hgp726d.7278#28...Packet received: OK
  Sending packet: $m4006b2,1#28...Packet received: e9
  Fast tracepoint 2 at 0x4006b2: file gdb/testsuite/gdb.trace/range-stepping.c, line 53.
  Sending packet: $qTStatus#49...Packet received: T0;tnotrun:0;tframes:0;tcreated:0;tfree:500000;tsize:500000;circular:0;disconn:0;starttime:0;stoptime:0;username:;notes::

This ended up breaking "tstart" when one has fast tracepoints set,
because gdbserver isn't expecting an Hg packet in response to
qRelocInsn:

 (gdb) ftrace *set_point
 Fast tracepoint 3 at 0x4006b2: file gdb/testsuite/gdb.trace/range-stepping.c, line 53.
 (gdb) PASS: gdb.trace/range-stepping.exp: ftrace: ftrace *set_point
 tstart
 gdbserver: Malformed response to qRelocInsn, ignoring: Hgp2783.2783

 Target does not support this command.
 (gdb) FAIL: gdb.trace/range-stepping.exp: ftrace: tstart

remote_trace_start should probably start by making sure the remote
current thread matches inferior_ptid (calling set_general_thread), but
still, reducing unnecessary bouncing is a good idea.  It happens
because the memory/symbol/breakpoint routines use
switch_to_program_space_and_thread to do something in the right
context and then revert back to the previously current thread.

The fix is to simply make any_thread_of_process,
find_inferior_for_program_space, etc. give preference to the current
thread/inferior it if matches.

gdb/
2014-10-02  Pedro Alves  <palves@redhat.com>

	* gdbthread.h (any_thread_of_process, any_live_thread_of_process):
	Adjust comments.
	* inferior.c (find_inferior_for_program_space): Give preference to
	the current inferior.
	* inferior.h (find_inferior_for_program_space): Update comment.
	* progspace.c (switch_to_program_space_and_thread): Prefer the
	current inferior if it's bound to the program space requested.  If
	the inferior found doesn't have a PID yet, don't bother looking up
	a thread.
	* progspace.h (switch_to_program_space_and_thread): Adjust
	comment.
	* thread.c (any_thread_of_process, any_live_thread_of_process):
	Give preference to the current thread.
This commit is contained in:
Pedro Alves
2014-10-02 09:55:38 +01:00
parent dac3fe8778
commit 32990adaad
7 changed files with 65 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
gdb/thread.c
View File

@ -466,7 +466,13 @@ any_thread_of_process (int pid)
{
struct thread_info *tp;
for (tp = thread_list; tp; tp = tp->next)
gdb_assert (pid != 0);
/* Prefer the current thread. */
if (ptid_get_pid (inferior_ptid) == pid)
return inferior_thread ();
ALL_NON_EXITED_THREADS (tp)
if (ptid_get_pid (tp->ptid) == pid)
return tp;
@ -476,18 +482,40 @@ any_thread_of_process (int pid)
struct thread_info *
any_live_thread_of_process (int pid)
{
struct thread_info *curr_tp = NULL;
struct thread_info *tp;
struct thread_info *tp_executing = NULL;
for (tp = thread_list; tp; tp = tp->next)
if (tp->state != THREAD_EXITED && ptid_get_pid (tp->ptid) == pid)
gdb_assert (pid != 0);
/* Prefer the current thread if it's not executing. */
if (ptid_get_pid (inferior_ptid) == pid)
{
/* If the current thread is dead, forget it. If it's not
executing, use it. Otherwise, still choose it (below), but
only if no other non-executing thread is found. */
curr_tp = inferior_thread ();
if (curr_tp->state == THREAD_EXITED)
curr_tp = NULL;
else if (!curr_tp->executing)
return curr_tp;
}
ALL_NON_EXITED_THREADS (tp)
if (ptid_get_pid (tp->ptid) == pid)
{
if (tp->executing)
tp_executing = tp;
else
if (!tp->executing)
return tp;
tp_executing = tp;
}
/* If both the current thread and all live threads are executing,
prefer the current thread. */
if (curr_tp != NULL)
return curr_tp;
/* Otherwise, just return an executing thread, if any. */
return tp_executing;
}