From d4cf3892e50b8e35341086a4fe2bb8a3989b55d4 Mon Sep 17 00:00:00 2001 From: Hollis Blanchard Date: Wed, 5 Nov 2008 09:36:23 -0600 Subject: KVM: ppc: optimize irq delivery path In kvmppc_deliver_interrupt is just one case left in the switch and it is a rare one (less than 8%) when looking at the exit numbers. Therefore we can at least drop the switch/case and if an if. I inserted an unlikely too, but that's open for discussion. In kvmppc_can_deliver_interrupt all frequent cases are in the default case. I know compilers are smart but we can make it easier for them. By writing down all options and removing the default case combined with the fact that ithe values are constants 0..15 should allow the compiler to write an easy jump table. Modifying kvmppc_can_deliver_interrupt pointed me to the fact that gcc seems to be unable to reduce priority_exception[x] to a build time constant. Therefore I changed the usage of the translation arrays in the interrupt delivery path completely. It is now using priority without translation to irq on the full irq delivery path. To be able to do that ivpr regs are stored by their priority now. Additionally the decision made in kvmppc_can_deliver_interrupt is already sufficient to get the value of interrupt_msr_mask[x]. Therefore we can replace the 16x4byte array used here with a single 4byte variable (might still be one miss, but the chance to find this in cache should be better than the right entry of the whole array). Signed-off-by: Christian Ehrhardt Signed-off-by: Hollis Blanchard Signed-off-by: Avi Kivity --- arch/powerpc/include/asm/kvm_ppc.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/powerpc/include/asm/kvm_ppc.h') diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 976ecc4b322e..844f683302f6 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -36,9 +36,6 @@ enum emulation_result { EMULATE_FAIL, /* can't emulate this instruction */ }; -extern const unsigned char exception_priority[]; -extern const unsigned char priority_exception[]; - extern int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu); extern char kvmppc_handlers_start[]; extern unsigned long kvmppc_handler_len; -- cgit v1.2.3