x86 uv: lower UV rtc clocksource rating

PATCH In review Dimitri Sivanich 2 participants 5 messages Feb 16, 2012 – Feb 20, 2012

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x86 x86 platform uv hpe superdome flex

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Dimitri Sivanich

author

2012-02-16 20:10 UTC #0 lore raw

PATCH 1/1 x86 uv: lower UV rtc clocksource rating

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

Signed-off-by Dimitri Sivanich <[email protected]>

---
 arch/x86/platform/uv/uv_time.c |    6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

arch/x86/platform/uv/uv_time.c +1 -5

Index: linux/arch/x86/platform/uv/uv_time.c
===================================================================
@@ -37,7 +37,7 @@ static void uv_rtc_timer_setup(enum cloc
 
 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(voi
 	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);

Ingo Molnar

2012-02-17 12:03 UTC #1 lore raw

Quoted 1 line · Dimitri Sivanich

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

This changelog is deficient for obvious reasons, mind updating it?

Thanks,

Ingo

Dimitri Sivanich

author

2012-02-17 14:16 UTC #2 lore raw

Quoted 8 lines · Ingo Molnar

Quoted 1 line · Dimitri Sivanich
Lower the rating of the UV rtc clocksource to just below that of the tsc.
This changelog is deficient for obvious reasons, mind updating it?

OK. Is this sufficient?

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

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 Dimitri Sivanich <[email protected]>

---
 arch/x86/platform/uv/uv_time.c |    6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

arch/x86/platform/uv/uv_time.c +1 -5

Index: linux/arch/x86/platform/uv/uv_time.c
===================================================================
@@ -37,7 +37,7 @@ static void uv_rtc_timer_setup(enum cloc
 
 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(voi
 	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);

Ingo Molnar

2012-02-19 12:51 UTC #3 lore raw

Quoted 9 lines · Dimitri Sivanich

Quoted 8 lines · Ingo Molnar
Quoted 1 line · Dimitri Sivanich
Lower the rating of the UV rtc clocksource to just below that of the tsc.
This changelog is deficient for obvious reasons, mind updating it?

Quoted 8 lines

OK. Is this sufficient?
Lower the rating of the UV rtc clocksource to just below that of the tsc.
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.

Yeah, perfect, thanks.

Ingo

tip-bot for Dimitri Sivanich

author

2012-02-20 11:47 UTC #4 lore raw

[tip:x86/uv] x86/UV: Lower UV rtc clocksource rating

In reply to Dimitri Sivanich

Commit-ID:  b0deca2e0270135f797e81bdb0743e50fd1dc58d
Gitweb:     http://git.kernel.org/tip/b0deca2e0270135f797e81bdb0743e50fd1dc58d
Author:     Dimitri Sivanich <[email protected]>
AuthorDate: Fri, 17 Feb 2012 08:16:41 -0600
Committer:  Ingo Molnar <[email protected]>
CommitDate: Mon, 20 Feb 2012 09:07:56 +0100

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.

Signed-off-by Dimitri Sivanich <[email protected]>

Cc John Stultz <[email protected]>

Cc Jack Steiner <[email protected]>

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Ingo Molnar <[email protected]>

---
 arch/x86/platform/uv/uv_time.c |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)

arch/x86/platform/uv/uv_time.c +1 -5

index 9f29a01..5032e0d 100644
@@ -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);