x86, pvticketlock: Use callee-save for lock_spinning

Although the lock_spinning calls in the spinlock code are on the uncommon path, their presence can cause the compiler to generate many more register save/restores in the function pre/postamble, which is in the fast path. To avoid this, convert it to using the pvops callee-save calling convention, which defers all the save/restores until the actual function is called, keeping the fastpath clean. Signed-off-by: Jeremy Fitzhardinge <[email protected]> Link: http://lkml.kernel.org/r/1376058122-8248-8-git-send-email-raghavendra.kt@linux.vnet.ibm.com Reviewed-by: Konrad Rzeszutek Wilk <[email protected]> Tested-by: Attilio Rao <[email protected]> Signed-off-by: Raghavendra K T <[email protected]> Acked-by: Ingo Molnar <[email protected]> Signed-off-by: H. Peter Anvin <[email protected]>
iegor · Aug 9, 2013 · 354714d · 354714d
1 parent b8fa70b
commit 354714d
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Showing 4 changed files with 5 additions and 4 deletions.
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
@@ -715,7 +715,7 @@ static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx,
 static __always_inline void __ticket_lock_spinning(struct arch_spinlock *lock,
 							__ticket_t ticket)
 {
-	PVOP_VCALL2(pv_lock_ops.lock_spinning, lock, ticket);
+	PVOP_VCALLEE2(pv_lock_ops.lock_spinning, lock, ticket);
 }
 
 static __always_inline void ____ticket_unlock_kick(struct arch_spinlock *lock,

diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
@@ -334,7 +334,7 @@ typedef u16 __ticket_t;
 #endif
 
 struct pv_lock_ops {
-	void (*lock_spinning)(struct arch_spinlock *lock, __ticket_t ticket);
+	struct paravirt_callee_save lock_spinning;
 	void (*unlock_kick)(struct arch_spinlock *lock, __ticket_t ticket);
 };
 

diff --git a/arch/x86/kernel/paravirt-spinlocks.c b/arch/x86/kernel/paravirt-spinlocks.c
@@ -9,7 +9,7 @@
 
 struct pv_lock_ops pv_lock_ops = {
 #ifdef CONFIG_SMP
-	.lock_spinning = paravirt_nop,
+	.lock_spinning = __PV_IS_CALLEE_SAVE(paravirt_nop),
 	.unlock_kick = paravirt_nop,
 #endif
 };

diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
@@ -173,6 +173,7 @@ static void xen_lock_spinning(struct arch_spinlock *lock, __ticket_t want)
 	local_irq_restore(flags);
 	spin_time_accum_blocked(start);
 }
+PV_CALLEE_SAVE_REGS_THUNK(xen_lock_spinning);
 
 static void xen_unlock_kick(struct arch_spinlock *lock, __ticket_t next)
 {
@@ -260,7 +261,7 @@ void __init xen_init_spinlocks(void)
 		return;
 	}
 
-	pv_lock_ops.lock_spinning = xen_lock_spinning;
+	pv_lock_ops.lock_spinning = PV_CALLEE_SAVE(xen_lock_spinning);
 	pv_lock_ops.unlock_kick = xen_unlock_kick;
 }