Commit 1f759bb3 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/time: use stck clock fast for do_account_vtime 



The last high frequency call site of the STCK instruction is
do_account_vtime. Replace it with the faster STCKF instruction.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent cac7f242

arch/s390/kernel/vtime.c

+4 −0
Original line number Diff line number Diff line
@@ -66,7 +66,11 @@ static int do_account_vtime(struct task_struct *tsk, int hardirq_offset) 
	clock = S390_lowcore.last_update_clock;

	asm volatile(

		"	stpt	%0\n"	/* Store current cpu timer value */

#ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES

		"	stckf	%1"	/* Store current tod clock value */

#else

		"	stck	%1"	/* Store current tod clock value */

#endif

		: "=m" (S390_lowcore.last_update_timer),

		  "=m" (S390_lowcore.last_update_clock));

	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;