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Message-Id: <20120321102159.473.94357.sendpatchset@codeblue.in.ibm.com>
Date: Wed, 21 Mar 2012 15:51:59 +0530
From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To: "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Peter Zijlstra <peterz@...radead.org>,
the arch/x86 maintainers <x86@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, Avi Kivity <avi@...hat.com>,
Marcelo Tosatti <mtosatti@...hat.com>,
KVM <kvm@...r.kernel.org>, Andi Kleen <andi@...stfloor.org>,
Xen Devel <xen-devel@...ts.xensource.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Virtualization <virtualization@...ts.linux-foundation.org>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>,
Stephan Diestelhorst <stephan.diestelhorst@....com>,
Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
Attilio Rao <attilio.rao@...rix.com>
Subject: [PATCH RFC V6 7/11] x86/pvticketlock: use callee-save for lock_spinning
From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
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.fitzhardinge@...rix.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
---
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;
}
--
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