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[review v2] Add maint set/show worker-threads
Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/174
......................................................................
Add maint set/show worker-threads
This adds maint commands to control the number of worker threads that
gdb can use.
gdb/ChangeLog
2019-10-19 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
2019-10-19 Tom Tromey <tom@tromey.com>
* gdb.texinfo (Maintenance Commands): Document new maint
commands.
Change-Id: I4fb514faa05879d8afe62c77036a4469d57dca2a
---
M gdb/ChangeLog
M gdb/NEWS
M gdb/doc/ChangeLog
M gdb/doc/gdb.texinfo
M gdb/maint.c
5 files changed, 84 insertions(+), 0 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 400ccc1..d7b40d7 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2019-10-19 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.
+
2019-10-19 Christian Biesinger <cbiesinger@google.com>
Tom Tromey <tom@tromey.com>
diff --git a/gdb/NEWS b/gdb/NEWS
index 25e67e4..7c98c14 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -134,6 +134,13 @@
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
diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 26f858f..175fc98 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,8 @@
+2019-10-19 Tom Tromey <tom@tromey.com>
+
+ * gdb.texinfo (Maintenance Commands): Document new maint
+ commands.
+
2019-10-07 Tom de Vries <tdevries@suse.de>
* gdb.texinfo: Fix typo.
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 1208e4f..3219e68 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -37683,6 +37683,21 @@
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
diff --git a/gdb/maint.c b/gdb/maint.c
index ec9f4ab..fce1a1c 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -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 +844,37 @@
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 ();
+ if (n_threads == 0)
+ {
+ /* Meh. */
+ n_threads = 2;
+ }
+ }
+
+ 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. */
@@ -1312,4 +1347,17 @@
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."), _("\
+Set 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 ();
}