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-rw-r--r--arch/x86/kernel/uv_time.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/arch/x86/kernel/uv_time.c b/arch/x86/kernel/uv_time.c
index 3c84aa001c1..2b75ef638db 100644
--- a/arch/x86/kernel/uv_time.c
+++ b/arch/x86/kernel/uv_time.c
@@ -282,10 +282,21 @@ static int uv_rtc_unset_timer(int cpu, int force)
/*
* Read the RTC.
+ *
+ * Starting with HUB rev 2.0, the UV RTC register is replicated across all
+ * cachelines of it's own page. This allows faster simultaneous reads
+ * from a given socket.
*/
static cycle_t uv_read_rtc(struct clocksource *cs)
{
- return (cycle_t)uv_read_local_mmr(UVH_RTC);
+ unsigned long offset;
+
+ if (uv_get_min_hub_revision_id() == 1)
+ offset = 0;
+ else
+ offset = (uv_blade_processor_id() * L1_CACHE_BYTES) % PAGE_SIZE;
+
+ return (cycle_t)uv_read_local_mmr(UVH_RTC | offset);
}
/*