[PATCH RFC V6 7/11] x86/pvticketlock: use callee-save for lock_spinning
From: Raghavendra K T <hidden>
Date: 2012-03-21 11:02:32
Also in:
kvm, lkml, xen-devel
Subsystem:
paravirt_ops interface, the rest, x86 architecture (32-bit and 64-bit), xen hypervisor x86 · Maintainers:
Juergen Gross, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: Jeremy Fitzhardinge <redacted> 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 <redacted> Reviewed-by: Konrad Rzeszutek Wilk <redacted> Signed-off-by: Raghavendra K T <redacted> --- arch/x86/include/asm/paravirt.h | 2 +- arch/x86/include/asm/paravirt_types.h | 2 +- arch/x86/kernel/paravirt-spinlocks.c | 2 +- arch/x86/xen/spinlock.c | 3 ++- 4 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 0fa4553..4343419 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h@@ -753,7 +753,7 @@ 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
index 005e24d..5e0c138 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h@@ -330,7 +330,7 @@ struct arch_spinlock; #include <asm/spinlock_types.h> 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
index c2e010e..4251c1d 100644
--- 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
index 5dce49d..176a554 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c@@ -173,6 +173,7 @@ out: 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) {
@@ -232,7 +233,7 @@ 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; }