From: Mario Smarduch <m.smarduch@samsung.com> To: kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, christoffer.dall@linaro.org Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, pbonzini@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, Mario Smarduch <m.smarduch@samsung.com> Subject: [PATCH 0/3] arm: KVM: VFP lazy switch in KVM Host Mode may save upto 98% Date: Wed, 24 Jun 2015 20:30:25 -0700 [thread overview] Message-ID: <1435203028-23142-1-git-send-email-m.smarduch@samsung.com> (raw) Currently we do a lazy VFP switch in Hyp mode, but once we exit and re-enter hyp mode we trap again on VFP access. This mode has shown around 30-50% improvement running hackbench and lmbench. This patch series extends lazy VFP switch beyond Hyp mode to KVM host mode. 1 - On guest access we switch from host to guest and set a flag accessible to host 2 - On exit to KVM host, VFP state is restored on vcpu_put if flag is marked (1) 3 - Otherwise guest is resumed and continues to use its VFP registers. 4 - In case of 2 on VM entry we set VFP trap flag to repeat 1. If guest does not access VFP registers them implemenation remains the same. Executing hackbench on Fast Models and Exynos arm32 board shows good results. Considering all exits 2% of the time KVM host lazy vfp switch is invoked. Howeverr this patch set requires more burn in time and testing under various loads. Currently ARM32 is addressed later ARM64. Mario Smarduch (3): define headers and offsets to mange VFP state Implement lazy VFP switching outside of Hyp Mode Add VFP lazy switch hooks in Host KVM arch/arm/include/asm/kvm_asm.h | 1 + arch/arm/include/asm/kvm_host.h | 3 +++ arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/arm.c | 15 ++++++++++++ arch/arm/kvm/interrupts.S | 49 +++++++++++++++++++++++++-------------- 5 files changed, 51 insertions(+), 18 deletions(-) -- 1.7.9.5
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From: m.smarduch@samsung.com (Mario Smarduch) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 0/3] arm: KVM: VFP lazy switch in KVM Host Mode may save upto 98% Date: Wed, 24 Jun 2015 20:30:25 -0700 [thread overview] Message-ID: <1435203028-23142-1-git-send-email-m.smarduch@samsung.com> (raw) Currently we do a lazy VFP switch in Hyp mode, but once we exit and re-enter hyp mode we trap again on VFP access. This mode has shown around 30-50% improvement running hackbench and lmbench. This patch series extends lazy VFP switch beyond Hyp mode to KVM host mode. 1 - On guest access we switch from host to guest and set a flag accessible to host 2 - On exit to KVM host, VFP state is restored on vcpu_put if flag is marked (1) 3 - Otherwise guest is resumed and continues to use its VFP registers. 4 - In case of 2 on VM entry we set VFP trap flag to repeat 1. If guest does not access VFP registers them implemenation remains the same. Executing hackbench on Fast Models and Exynos arm32 board shows good results. Considering all exits 2% of the time KVM host lazy vfp switch is invoked. Howeverr this patch set requires more burn in time and testing under various loads. Currently ARM32 is addressed later ARM64. Mario Smarduch (3): define headers and offsets to mange VFP state Implement lazy VFP switching outside of Hyp Mode Add VFP lazy switch hooks in Host KVM arch/arm/include/asm/kvm_asm.h | 1 + arch/arm/include/asm/kvm_host.h | 3 +++ arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/arm.c | 15 ++++++++++++ arch/arm/kvm/interrupts.S | 49 +++++++++++++++++++++++++-------------- 5 files changed, 51 insertions(+), 18 deletions(-) -- 1.7.9.5
next reply other threads:[~2015-06-25 3:30 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-25 3:30 Mario Smarduch [this message] 2015-06-25 3:30 ` [PATCH 0/3] arm: KVM: VFP lazy switch in KVM Host Mode may save upto 98% Mario Smarduch 2015-06-25 3:30 ` [PATCH 1/3] arm: KVM: define headers and offsets to mange VFP state Mario Smarduch 2015-06-25 3:30 ` Mario Smarduch 2015-07-05 19:27 ` Christoffer Dall 2015-07-05 19:27 ` Christoffer Dall 2015-07-06 17:50 ` Mario Smarduch 2015-07-06 17:50 ` Mario Smarduch 2015-06-25 3:30 ` [PATCH 2/3] arm: KVM: Implement lazy VFP switching outside of Hyp Mode Mario Smarduch 2015-06-25 3:30 ` Mario Smarduch 2015-07-05 19:34 ` Christoffer Dall 2015-07-05 19:34 ` Christoffer Dall 2015-07-06 17:54 ` Mario Smarduch 2015-07-06 17:54 ` Mario Smarduch 2015-07-07 15:27 ` Christoffer Dall 2015-07-07 15:27 ` Christoffer Dall 2015-06-25 3:30 ` [PATCH 3/3] arm: KVM: Add VFP lazy switch hooks in Host KVM Mario Smarduch 2015-06-25 3:30 ` Mario Smarduch 2015-07-05 19:37 ` Christoffer Dall 2015-07-05 19:37 ` Christoffer Dall 2015-07-06 18:35 ` Mario Smarduch 2015-07-06 18:35 ` Mario Smarduch 2015-06-28 17:57 ` [PATCH 0/3] arm: KVM: VFP lazy switch in KVM Host Mode may save upto 98% Mario Smarduch 2015-06-28 17:57 ` Mario Smarduch 2015-07-05 19:37 ` Christoffer Dall 2015-07-05 19:37 ` Christoffer Dall 2015-07-06 18:43 ` Mario Smarduch 2015-07-06 18:43 ` Mario Smarduch
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