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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 <jeremy@goop.org>
Link: http://lkml.kernel.org/r/1376058122-8248-8-git-send-email-raghavendra.kt@linux.vnet.ibm.com
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Tested-by: Attilio Rao <attilio.rao@citrix.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Jeremy Fitzhardinge 2013-08-09 19:51:55 +05:30 committed by H. Peter Anvin
parent b8fa70b51a
commit 354714dd26
4 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/paravirt.h
View File

@ -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,

2
arch/x86/include/asm/paravirt_types.h
View File

@ -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);
};

2
arch/x86/kernel/paravirt-spinlocks.c
View File

@ -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
};

3
arch/x86/xen/spinlock.c
View File

@ -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;
}