Add maint set/show worker-threads

This adds maint commands to control the number of worker threads that
gdb can use.

2019-11-26  Tom Tromey  <tom@tromey.com>

	* NEWS: Add entry.
	* maint.c (_initialize_maint_cmds): Add "worker-threads" maint
	commands.  Call update_thread_pool_size.
	(update_thread_pool_size, maintenance_set_worker_threads): New
	functions.
	(n_worker_threads): New global.

gdb/doc/ChangeLog
2019-11-26  Tom Tromey  <tom@tromey.com>

	* gdb.texinfo (Maintenance Commands): Document new maint
	commands.

Change-Id: I4fb514faa05879d8afe62c77036a4469d57dca2a
This commit is contained in:
Tom Tromey 2019-03-16 14:36:57 -06:00
parent d55c9a6847
commit 22138db609
5 changed files with 77 additions and 0 deletions

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@ -1,3 +1,12 @@
2019-11-26 Tom Tromey <tom@tromey.com>
* NEWS: Add entry.
* maint.c (_initialize_maint_cmds): Add "worker-threads" maint
commands. Call update_thread_pool_size.
(update_thread_pool_size, maintenance_set_worker_threads): New
functions.
(n_worker_threads): New global.
2019-11-26 Christian Biesinger <cbiesinger@google.com>
Tom Tromey <tom@tromey.com>

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@ -149,6 +149,13 @@ set style highlight background COLOR
set style highlight intensity VALUE
Control the styling of highlightings.
maint set worker-threads
maint show worker-threads
Control the number of worker threads that can be used by GDB. The
default is "unlimited", which lets GDB choose a number that is
reasonable. Currently worker threads are only used when demangling
the names of linker symbols.
maint set test-settings KIND
maint show test-settings KIND
A set of commands used by the testsuite for exercising the settings

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@ -1,3 +1,8 @@
2019-11-26 Tom Tromey <tom@tromey.com>
* gdb.texinfo (Maintenance Commands): Document new maint
commands.
2019-11-25 Luis Machado <luis.machado@linaro.org>
* gdb.texinfo (Debugging Output): Document set debug

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@ -37876,6 +37876,21 @@ with the DWARF frame unwinders enabled.
If DWARF frame unwinders are not supported for a particular target
architecture, then enabling this flag does not cause them to be used.
@kindex maint set worker-threads
@kindex maint show worker-threads
@item maint set worker-threads
@item maint show worker-threads
Control the number of worker threads that may be used by @value{GDBN}.
On capable hosts, @value{GDBN} may use multiple threads to speed up
certain CPU-intensive operations, such as demangling symbol names.
While the number of threads used by @value{GDBN} may vary, this
command can be used to set an upper bound on this number. The default
is @code{unlimited}, which lets @value{GDBN} choose a reasonable
number. Note that this only controls worker threads started by
@value{GDBN} itself; libraries used by @value{GDBN} may start threads
of their own.
@kindex maint set profile
@kindex maint show profile
@cindex profiling GDB

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@ -46,6 +46,10 @@
#include "cli/cli-setshow.h"
#include "cli/cli-cmds.h"
#if CXX_STD_THREAD
#include "gdbsupport/thread-pool.h"
#endif
static void maintenance_do_deprecate (const char *, int);
/* Access the maintenance subcommands. */
@ -840,6 +844,30 @@ maintenance_set_profile_cmd (const char *args, int from_tty,
error (_("Profiling support is not available on this system."));
}
#endif
static int n_worker_threads = -1;
/* Update the thread pool for the desired number of threads. */
static void
update_thread_pool_size ()
{
#if CXX_STD_THREAD
int n_threads = n_worker_threads;
if (n_threads < 0)
n_threads = std::thread::hardware_concurrency ();
gdb::thread_pool::g_thread_pool->set_thread_count (n_threads);
#endif
}
static void
maintenance_set_worker_threads (const char *args, int from_tty,
struct cmd_list_element *c)
{
update_thread_pool_size ();
}
/* If true, display time usage both at startup and for each command. */
@ -1313,4 +1341,17 @@ When enabled GDB is profiled."),
show_maintenance_profile_p,
&maintenance_set_cmdlist,
&maintenance_show_cmdlist);
add_setshow_zuinteger_unlimited_cmd ("worker-threads",
class_maintenance,
&n_worker_threads, _("\
Set the number of worker threads GDB can use."), _("\
Show the number of worker threads GDB can use."), _("\
GDB may use multiple threads to speed up certain CPU-intensive operations,\n\
such as demangling symbol names."),
maintenance_set_worker_threads, NULL,
&maintenance_set_cmdlist,
&maintenance_show_cmdlist);
update_thread_pool_size ();
}