Messages in this thread | | | Date | Wed, 11 Oct 2017 12:49:05 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v2 4/5] arm64: locking: Move rwlock implementation over to qrwlocks |
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Hi Waiman,
On Mon, Oct 09, 2017 at 09:34:08PM -0400, Waiman Long wrote: > On 10/06/2017 09:34 AM, Will Deacon wrote: > > Now that the qrwlock can make use of WFE, remove our homebrew rwlock > > code in favour of the generic queued implementation. > > > > Signed-off-by: Will Deacon <will.deacon@arm.com> > > --- > > arch/arm64/Kconfig | 17 ++++ > > arch/arm64/include/asm/Kbuild | 1 + > > arch/arm64/include/asm/spinlock.h | 164 +------------------------------- > > arch/arm64/include/asm/spinlock_types.h | 6 +- > > 4 files changed, 20 insertions(+), 168 deletions(-) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index 0df64a6a56d4..6d32c9b0d4bb 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -22,7 +22,24 @@ config ARM64 > > select ARCH_HAS_STRICT_MODULE_RWX > > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > > select ARCH_HAVE_NMI_SAFE_CMPXCHG if ACPI_APEI_SEA > > + select ARCH_INLINE_READ_LOCK if !PREEMPT > > + select ARCH_INLINE_READ_LOCK_BH if !PREEMPT > > + select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPT > > + select ARCH_INLINE_READ_LOCK_IRQSAVE if !PREEMPT > > + select ARCH_INLINE_READ_UNLOCK if !PREEMPT > > + select ARCH_INLINE_READ_UNLOCK_BH if !PREEMPT > > + select ARCH_INLINE_READ_UNLOCK_IRQ if !PREEMPT > > + select ARCH_INLINE_READ_UNLOCK_IRQSAVE if !PREEMPT > > + select ARCH_INLINE_WRITE_LOCK if !PREEMPT > > + select ARCH_INLINE_WRITE_LOCK_BH if !PREEMPT > > + select ARCH_INLINE_WRITE_LOCK_IRQ if !PREEMPT > > + select ARCH_INLINE_WRITE_LOCK_IRQSAVE if !PREEMPT > > + select ARCH_INLINE_WRITE_UNLOCK if !PREEMPT > > + select ARCH_INLINE_WRITE_UNLOCK_BH if !PREEMPT > > + select ARCH_INLINE_WRITE_UNLOCK_IRQ if !PREEMPT > > + select ARCH_INLINE_WRITE_UNLOCK_IRQSAVE if !PREEMPT > > select ARCH_USE_CMPXCHG_LOCKREF > > + select ARCH_USE_QUEUED_RWLOCKS > > select ARCH_SUPPORTS_MEMORY_FAILURE > > select ARCH_SUPPORTS_ATOMIC_RMW > > select ARCH_SUPPORTS_NUMA_BALANCING > > Inlining is good for performance, but it may come with an increase in > kernel text size. Inlining unlock and unlock_irq are OK, but the other > inlines will increase the text size of the kernel. Have you measured how > much size increase will that be? Is there any concern about the > increased text size?
Yes, I did look at the disassembly and bloat-o-meter results. Inlining these functions means that the fastpath sits entirely within a 64-byte cacheline and bloat-o-meter shows a relatively small increase in vmlinux size for a defconfig build with CONFIG_PREEMPT disabled:
Total: Before=13800924, After=13812904, chg +0.09%
(I also just noticed my typos in ARCH_INLINE_{READ.WRITE}_UNLOCK_IRQSAVE so I regenerated the numbers!)
Will
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