find below a patch with less impact than blanket upwards rounding of
relatime timeouts. This i think is better for v2.6.16 - it accurately
documents the problem architectures that have low-res do_gettimeofday(),
and doesnt impact other architectures. This will go away with John's
GTOD patchset. I've reviewed every architecture for the (worst-case)
resolution of their do_gettimeofday() implementations, and this is the
result of that review.
Ingo
-----
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 <[email protected]>
----
arch/frv/Kconfig | 4 ++++
arch/h8300/Kconfig | 4 ++++
arch/m68k/Kconfig | 4 ++++
arch/m68knommu/Kconfig | 4 ++++
arch/parisc/Kconfig | 5 +++++
arch/v850/Kconfig | 4 ++++
kernel/hrtimer.c | 13 ++++++++++++-
7 files changed, 37 insertions(+), 1 deletion(-)
Index: linux/arch/frv/Kconfig
===================================================================
--- linux.orig/arch/frv/Kconfig
+++ linux/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"
Index: linux/arch/h8300/Kconfig
===================================================================
--- linux.orig/arch/h8300/Kconfig
+++ linux/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
Index: linux/arch/m68k/Kconfig
===================================================================
--- linux.orig/arch/m68k/Kconfig
+++ linux/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)
Index: linux/arch/m68knommu/Kconfig
===================================================================
--- linux.orig/arch/m68knommu/Kconfig
+++ linux/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"
Index: linux/arch/parisc/Kconfig
===================================================================
--- linux.orig/arch/parisc/Kconfig
+++ linux/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
Index: linux/arch/v850/Kconfig
===================================================================
--- linux.orig/arch/v850/Kconfig
+++ linux/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
Index: linux/kernel/hrtimer.c
===================================================================
--- linux.orig/kernel/hrtimer.c
+++ linux/kernel/hrtimer.c
@@ -418,8 +418,19 @@ hrtimer_start(struct hrtimer *timer, kti
/* 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);
-
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