On Intel systems generally the TSC stops in C3 or deeper,
so don't use it there. Follows similar logic on i386.
This should fix problems on Meroms.
Signed-off-by: Andi Kleen <[email protected]>
---
arch/x86_64/kernel/time.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
Index: linux-2.6.18-rc2-git7/arch/x86_64/kernel/time.c
===================================================================
--- linux-2.6.18-rc2-git7.orig/arch/x86_64/kernel/time.c
+++ linux-2.6.18-rc2-git7/arch/x86_64/kernel/time.c
@@ -28,6 +28,7 @@
#include <linux/acpi.h>
#ifdef CONFIG_ACPI
#include <acpi/achware.h> /* for PM timer frequency */
+#include <acpi/acpi_bus.h>
#endif
#include <asm/8253pit.h>
#include <asm/pgtable.h>
@@ -953,11 +954,18 @@ __cpuinit int unsynchronized_tsc(void)
#ifdef CONFIG_SMP
if (apic_is_clustered_box())
return 1;
- /* Intel systems are normally all synchronized. Exceptions
- are handled in the check above. */
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
- return 0;
#endif
+ /* Most intel systems have synchronized TSCs except for
+ multi node systems */
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
+#ifdef CONFIG_ACPI
+ /* But TSC doesn't tick in C3 so don't use it there */
+ if (acpi_fadt.length > 0 && acpi_fadt.plvl3_lat < 100)
+ return 1;
+#endif
+ return 0;
+ }
+
/* Assume multi socket systems are not synchronized */
return num_present_cpus() > 1;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
