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Commit 354714dd authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by H. Peter Anvin
Browse files

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: default avatarJeremy Fitzhardinge <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-8-git-send-email-raghavendra.kt@linux.vnet.ibm.com


Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: default avatarAttilio Rao <attilio.rao@citrix.com>
Signed-off-by: default avatarRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent b8fa70b5

arch/x86/include/asm/paravirt.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

arch/x86/include/asm/paravirt_types.h

+1 −1
Original line number Diff line number Diff line
@@ -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);

};

arch/x86/kernel/paravirt-spinlocks.c

+1 −1
Original line number Diff line number Diff line
@@ -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

};

arch/x86/xen/spinlock.c

+2 −1
Original line number Diff line number Diff line
@@ -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;

}