Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1dcc8d7b authored by Suresh Siddha's avatar Suresh Siddha Committed by H. Peter Anvin
Browse files

x86, fpu: drop the fpu state during thread exit 



There is no need to save any active fpu state to the task structure
memory if the task is dead. Just drop the state instead.

For example, this saved some 1770 xsave's during the system boot
of a two socket Xeon system.

Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Link: http://lkml.kernel.org/r/1336692811-30576-4-git-send-email-suresh.b.siddha@intel.com


Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent d75f1b39

arch/x86/kernel/process.c

+13 −6
Original line number Diff line number Diff line
@@ -87,6 +87,16 @@ void arch_task_cache_init(void) 
				  SLAB_PANIC | SLAB_NOTRACK, NULL);

}



static inline void drop_fpu(struct task_struct *tsk)

{

	/*

	 * Forget coprocessor state..

	 */

	tsk->fpu_counter = 0;

	clear_fpu(tsk);

	clear_used_math();

}



/*

 * Free current thread data structures etc..

 */
@@ -109,6 +119,8 @@ void exit_thread(void) 
		put_cpu();

		kfree(bp);

	}



	drop_fpu(me);

}



void show_regs(struct pt_regs *regs)
@@ -149,12 +161,7 @@ void flush_thread(void) 


	flush_ptrace_hw_breakpoint(tsk);

	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));

	/*

	 * Forget coprocessor state..

	 */

	tsk->fpu_counter = 0;

	clear_fpu(tsk);

	clear_used_math();

	drop_fpu(tsk);

}



static void hard_disable_TSC(void)