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

Commit b0deca2e authored by Dimitri Sivanich's avatar Dimitri Sivanich Committed by Ingo Molnar
Browse files

x86/UV: Lower UV rtc clocksource rating 



Lower the rating of the UV rtc clocksource to just below that of
the tsc, to improve performance.

Reading the tsc clocksource has lower latency than reading the
rtc, so favor it in situations where it is synchronized and
stable.  When the tsc is unsynchronized, the rtc needs to be the
chosen clocksource.

Signed-off-by: default avatarDimitri Sivanich <sivanich@sgi.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Jack Steiner <steiner@sgi.com>
Link: http://lkml.kernel.org/r/20120217141641.GA28063@sgi.com


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b01543df

arch/x86/platform/uv/uv_time.c

+1 −5
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ static void uv_rtc_timer_setup(enum clock_event_mode, 


static struct clocksource clocksource_uv = {

	.name		= RTC_NAME,

	.rating		= 400,

	.rating		= 299,

	.read		= uv_read_rtc,

	.mask		= (cycle_t)UVH_RTC_REAL_TIME_CLOCK_MASK,

	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
@@ -379,10 +379,6 @@ static __init int uv_rtc_setup_clock(void) 
	if (!is_uv_system())

		return -ENODEV;



	/* If single blade, prefer tsc */

	if (uv_num_possible_blades() == 1)

		clocksource_uv.rating = 250;



	rc = clocksource_register_hz(&clocksource_uv, sn_rtc_cycles_per_second);

	if (rc)

		printk(KERN_INFO "UV RTC clocksource failed rc %d\n", rc);