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[PATCH RFC v2 5/5] x86/mwait-idle: squash stats update when not actually entering C-state
- To: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Thu, 20 Jan 2022 15:05:12 +0100
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
- Delivery-date: Thu, 20 Jan 2022 14:05:19 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
While we don't want to skip calling update_idle_stats(), arrange for it
to not increment the overall time spent in the state we didn't really
enter.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
RFC: Arguably more of what follows could be moved into the if() -
thoughts?
---
v2: New.
--- a/xen/arch/x86/cpu/mwait-idle.c
+++ b/xen/arch/x86/cpu/mwait-idle.c
@@ -861,9 +861,11 @@ static void mwait_idle(void)
mwait_idle_with_hints(cx->address, MWAIT_ECX_INTERRUPT_BREAK);
local_irq_disable();
- }
- after = alternative_call(cpuidle_get_tick);
+ after = alternative_call(cpuidle_get_tick);
+ }
+ else
+ before = after = alternative_call(cpuidle_get_tick);
cstate_restore_tsc();
trace_exit_reason(irq_traced);
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