Re: [PATCH][fix for gdb/15853] 'thread apply all inetrrupt&' shows inefficiency on remote targets

[Yao Qi <yao at codesourcery dot com>]

On 08/27/2013 10:00 PM, Muhammad Bilal wrote:
> In the case of 'interrupt -a&' command gdb sends only one packet to
> stop all  threads as $vCont;t#b9...

Here is the doc on "interrupt -a",

interrupt
interrupt -a
Suspend execution of the running program. In all-stop mode, interrupt
stops the whole process, but in non-stop mode, it stops only the
current thread. To stop the whole program in non-stop mode, use
interrupt -a.

The "whole program" is ambiguous in multi-process debugging.  IMO, 
"whole program" means the process.  That is to say, "interrupt -a" only 
applies to the threads in the process.  Threads in other processes are 
not affected.  However, that is not true.  I tried "interrupt -a" in a
multi-inferior of multi-thread program, it stops *all* threads in *all*
inferiors.

The comments are clear,

/* Stop the execution of the target while running in async mode, in
   the backgound.  In all-stop, stop the whole process.  In non-stop
   mode, stop the current thread only by default, or stop all threads
   if the `-a' switch is used.  */

/* interrupt [-a]  */
static void
interrupt_target_command (char *args, int from_tty)

What is the expect scope of "interrupt -a"? current process or all 
processes?

> But in case of 'thread apply all interrupt&' GDB issues individual
> packet for each thread.I think that In non-stop mode
> 'interrupt -a&' and 'thread apply all interrupt&' commands are equals
> but time efficiency of later command is less.
>
> Also,
>
> If user issues a command like 'thread apply all interrupt -a&'
> GDB accepts it and GDB will stop all threads on first vcount;t packets
> but due to loops iteration on all threads,
> GDB sends vcount;t packet for all remaining threads although GDB has
> already stop all thread so IMO it is a bug.

It is less efficient, but not a bug me.  Optimization to this special 
case looks not good to me.  It adds extra complexities, but the gain is 
limited AFAICS.

IMO, the real program here is that we need ITSET to describe a
set of arbitrary processes and thread to the remote target through
protocol.

  $vCont;t:[t7786-7788] // stop thread 7786 to thread 7788.

--
Yao (éå)