Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead
On Tue, 16 Jun 2015, Juergen Gross wrote: > AFAIK there are no outstanding questions for more than one month now. > I'd appreciate some feedback or accepting these patches. They are against dead code, which will be gone soon. We switched over to queued locks. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead
AFAIK there are no outstanding questions for more than one month now. I'd appreciate some feedback or accepting these patches. Juergen On 04/30/2015 12:53 PM, Juergen Gross wrote: Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvops functions to reduce the size of the inlined spinlock functions. When running on bare metal unlocking is again basically one instruction. Compile tested with CONFIG_PARAVIRT_SPINLOCKS on and off, 32 and 64 bits. Functional testing on bare metal and as Xen dom0. Correct patching verified by disassembly of active kernel. Juergen Gross (6): x86: use macro instead of "0" for setting TICKET_SLOWPATH_FLAG x86: move decision about clearing slowpath flag into arch_spin_lock() x86: introduce new pvops function clear_slowpath x86: introduce new pvops function spin_unlock x86: switch config from UNINLINE_SPIN_UNLOCK to INLINE_SPIN_UNLOCK x86: remove no longer needed paravirt_ticketlocks_enabled arch/x86/Kconfig | 1 - arch/x86/include/asm/paravirt.h | 13 + arch/x86/include/asm/paravirt_types.h | 12 arch/x86/include/asm/spinlock.h | 53 --- arch/x86/include/asm/spinlock_types.h | 3 +- arch/x86/kernel/kvm.c | 14 + arch/x86/kernel/paravirt-spinlocks.c | 42 +-- arch/x86/kernel/paravirt.c| 12 arch/x86/kernel/paravirt_patch_32.c | 25 + arch/x86/kernel/paravirt_patch_64.c | 24 arch/x86/xen/spinlock.c | 23 +-- include/linux/spinlock_api_smp.h | 2 +- kernel/Kconfig.locks | 7 +++-- kernel/Kconfig.preempt| 3 +- kernel/locking/spinlock.c | 2 +- lib/Kconfig.debug | 1 - 16 files changed, 154 insertions(+), 83 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead
Ping? Anything missing from my side? On 04/30/2015 12:53 PM, Juergen Gross wrote: Paravirtualized spinlocks produce some overhead even if the kernel is running on bare metal. The main reason are the more complex locking and unlocking functions. Especially unlocking is no longer just one instruction but so complex that it is no longer inlined. This patch series addresses this issue by adding two more pvops functions to reduce the size of the inlined spinlock functions. When running on bare metal unlocking is again basically one instruction. Compile tested with CONFIG_PARAVIRT_SPINLOCKS on and off, 32 and 64 bits. Functional testing on bare metal and as Xen dom0. Correct patching verified by disassembly of active kernel. Juergen Gross (6): x86: use macro instead of "0" for setting TICKET_SLOWPATH_FLAG x86: move decision about clearing slowpath flag into arch_spin_lock() x86: introduce new pvops function clear_slowpath x86: introduce new pvops function spin_unlock x86: switch config from UNINLINE_SPIN_UNLOCK to INLINE_SPIN_UNLOCK x86: remove no longer needed paravirt_ticketlocks_enabled arch/x86/Kconfig | 1 - arch/x86/include/asm/paravirt.h | 13 + arch/x86/include/asm/paravirt_types.h | 12 arch/x86/include/asm/spinlock.h | 53 --- arch/x86/include/asm/spinlock_types.h | 3 +- arch/x86/kernel/kvm.c | 14 + arch/x86/kernel/paravirt-spinlocks.c | 42 +-- arch/x86/kernel/paravirt.c| 12 arch/x86/kernel/paravirt_patch_32.c | 25 + arch/x86/kernel/paravirt_patch_64.c | 24 arch/x86/xen/spinlock.c | 23 +-- include/linux/spinlock_api_smp.h | 2 +- kernel/Kconfig.locks | 7 +++-- kernel/Kconfig.preempt| 3 +- kernel/locking/spinlock.c | 2 +- lib/Kconfig.debug | 1 - 16 files changed, 154 insertions(+), 83 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 0/6] x86: reduce paravirtualized spinlock overhead
On 04/30/2015 03:53 AM, Juergen Gross wrote: > Paravirtualized spinlocks produce some overhead even if the kernel is > running on bare metal. The main reason are the more complex locking > and unlocking functions. Especially unlocking is no longer just one > instruction but so complex that it is no longer inlined. > > This patch series addresses this issue by adding two more pvops > functions to reduce the size of the inlined spinlock functions. When > running on bare metal unlocking is again basically one instruction. Out of curiosity, is there a measurable difference? J -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
