Make ADAPTIVE_GIANT as the default in the kernel and remove the option.

Currently, Giant is not too much contented so that it is ok to treact it
like any other mutexes.

Please don't forget to update your own custom config kernel files.

Approved by:	cognet, marcel (maintainers of arches where option is
		not enabled at the moment)

sys/amd64/conf/GENERIC

@@ -59,7 +59,6 @@ options 	SYSVMSG			# SYSV-style message queues
 options 	SYSVSEM			# SYSV-style semaphores
 options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
 options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
-options 	ADAPTIVE_GIANT		# Giant mutex is adaptive.
 options 	STOP_NMI		# Stop CPUS using NMI instead of IPI
 options 	AUDIT			# Security event auditing
 

sys/conf/NOTES

@@ -206,12 +206,6 @@ options 	NO_ADAPTIVE_MUTEXES
 # to disable it.
 options 	NO_ADAPTIVE_RWLOCKS
 
-# ADAPTIVE_GIANT causes the Giant lock to also be made adaptive when
-# running without NO_ADAPTIVE_MUTEXES.  Normally, because Giant is assumed
-# to be held for extended periods, contention on Giant will cause a thread
-# to sleep rather than spinning.
-options 	ADAPTIVE_GIANT
-
 # ADAPTIVE_SX changes the behavior of sx locks to spin if the thread
 # that currently owns the lock is executing on another CPU.  Note that
 # in addition to enabling this option, individual sx locks must be

sys/conf/options

@@ -58,7 +58,6 @@ SYSCTL_DEBUG	opt_sysctl.h
 NO_SYSCTL_DESCR	opt_global.h
 
 # Miscellaneous options.
-ADAPTIVE_GIANT	opt_adaptive_mutexes.h
 ADAPTIVE_SX
 ALQ
 AUDIT		opt_global.h

sys/i386/conf/GENERIC

@@ -59,7 +59,6 @@ options 	SYSVMSG			# SYSV-style message queues
 options 	SYSVSEM			# SYSV-style semaphores
 options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
 options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
-options 	ADAPTIVE_GIANT		# Giant mutex is adaptive.
 options 	STOP_NMI		# Stop CPUS using NMI instead of IPI
 options 	AUDIT			# Security event auditing
 

sys/i386/conf/XBOX

@@ -41,7 +41,6 @@ options 	CD9660			# ISO 9660 Filesystem
 #options 	SYSVSEM			# SYSV-style semaphores
 #options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
 #options 	KBD_INSTALL_CDEV	# install a CDEV entry in /dev
-options 	ADAPTIVE_GIANT		# Giant mutex is adaptive.
 # Xbox has a non-standard default timer frequency
 options 	TIMER_FREQ=1125000	# Gives ~733.34MHz CPU
 

sys/kern/kern_mutex.c

@@ -343,11 +343,7 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
 		v = m->mtx_lock;
 		if (v != MTX_UNOWNED) {
 			owner = (struct thread *)(v & ~MTX_FLAGMASK);
-#ifdef ADAPTIVE_GIANT
 			if (TD_IS_RUNNING(owner)) {
-#else
-			if (m != &Giant && TD_IS_RUNNING(owner)) {
-#endif
 				if (LOCK_LOG_TEST(&m->lock_object, 0))
 					CTR3(KTR_LOCK,
 					    "%s: spinning on %p held by %p",
@@ -381,11 +377,7 @@ _mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
 		 * CPU quit the hard path and try to spin.
 		 */
 		owner = (struct thread *)(v & ~MTX_FLAGMASK);
-#ifdef ADAPTIVE_GIANT
 		if (TD_IS_RUNNING(owner)) {
-#else
-		if (m != &Giant && TD_IS_RUNNING(owner)) {
-#endif
 			turnstile_cancel(ts);
 			cpu_spinwait();
 			continue;

sys/sparc64/conf/GENERIC

@@ -60,7 +60,6 @@ options 	SYSVSHM			# SYSV-style shared memory
 options 	SYSVMSG			# SYSV-style message queues
 options 	SYSVSEM			# SYSV-style semaphores
 options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
-options 	ADAPTIVE_GIANT		# Giant mutex is adaptive.
 options 	AUDIT			# Security event auditing
 
 # Debugging for use in -current

sys/sun4v/conf/GENERIC

@@ -61,7 +61,6 @@ options 	SYSVSEM			# SYSV-style semaphores
 options 	_KPOSIX_PRIORITY_SCHEDULING # POSIX P1003_1B real-time extensions
 options 	AHC_REG_PRETTY_PRINT	# Print register bitfields in debug
 					# output.  Adds ~128k to driver.
-options 	ADAPTIVE_GIANT		# Giant mutex is adaptive.
 options 	PRINTF_BUFR_SIZE=128	# Prevent printf output being interspersed.
 options 	AUDIT			# Security event auditing