[PATCH] hrtimer: round up relative start time on low-res arches

CONFIG_TIME_LOW_RES is a temporary way for architectures to signal that they simply return xtime in do_gettimeoffset(). In this corner-case we want to round up by resolution when starting a relative timer, to avoid short timeouts. This will go away with the GTOD framework. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
git-mirror · Feb 15, 2006 · 06027bd · 06027bd
1 parent e35a661
commit 06027bd
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Showing 7 changed files with 37 additions and 1 deletion.
diff --git a/arch/frv/Kconfig b/arch/frv/Kconfig
@@ -25,6 +25,10 @@ config GENERIC_HARDIRQS
 	bool
 	default n
 
+config TIME_LOW_RES
+	bool
+	default y
+
 mainmenu "Fujitsu FR-V Kernel Configuration"
 
 source "init/Kconfig"

diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
@@ -33,6 +33,10 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
+config TIME_LOW_RES
+	bool
+	default y
+
 config ISA
 	bool
 	default y

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
@@ -21,6 +21,10 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
+config TIME_LOW_RES
+	bool
+	default y
+
 config ARCH_MAY_HAVE_PC_FDC
 	bool
 	depends on Q40 || (BROKEN && SUN3X)

diff --git a/arch/m68knommu/Kconfig b/arch/m68knommu/Kconfig
@@ -29,6 +29,10 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
+config TIME_LOW_RES
+	bool
+	default y
+
 source "init/Kconfig"
 
 menu "Processor type and features"

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
@@ -29,6 +29,11 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
+config TIME_LOW_RES
+	bool
+	depends on SMP
+	default y
+
 config GENERIC_ISA_DMA
 	bool
 

diff --git a/arch/v850/Kconfig b/arch/v850/Kconfig
@@ -28,6 +28,10 @@ config GENERIC_IRQ_PROBE
 	bool
 	default y
 
+config TIME_LOW_RES
+	bool
+	default y
+
 # Turn off some random 386 crap that can affect device config
 config ISA
 	bool

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
@@ -418,8 +418,19 @@ hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
 	/* Switch the timer base, if necessary: */
 	new_base = switch_hrtimer_base(timer, base);
 
-	if (mode == HRTIMER_REL)
+	if (mode == HRTIMER_REL) {
 		tim = ktime_add(tim, new_base->get_time());
+		/*
+		 * CONFIG_TIME_LOW_RES is a temporary way for architectures
+		 * to signal that they simply return xtime in
+		 * do_gettimeoffset(). In this case we want to round up by
+		 * resolution when starting a relative timer, to avoid short
+		 * timeouts. This will go away with the GTOD framework.
+		 */
+#ifdef CONFIG_TIME_LOW_RES
+		tim = ktime_add(tim, base->resolution);
+#endif
+	}
 	timer->expires = tim;
 
 	enqueue_hrtimer(timer, new_base);