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[1/2] KVM: PPC: Book3S: PR: Optimize entry path

Message ID 1335357502-30113-1-git-send-email-agraf@suse.de
State New, archived
Headers show

Commit Message

Alexander Graf April 25, 2012, 12:38 p.m. UTC 
By shuffling a few instructions around we can execute more memory
loads in parallel, giving us a small performance boost.

With this patch and a simple priviledged SPR access loop guest, I get
a speed bump from 2013052 to 2035607 exits per second.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/kvm/book3s_segment.S |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)
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Patch

diff --git a/arch/powerpc/kvm/book3s_segment.S b/arch/powerpc/kvm/book3s_segment.S
index 64f9018..f34a070 100644
--- a/arch/powerpc/kvm/book3s_segment.S
+++ b/arch/powerpc/kvm/book3s_segment.S
@@ -128,24 +128,25 @@  no_dcbz32_on:
 	/* First clear RI in our current MSR value */
 	li	r0, MSR_RI
 	andc	r6, r6, r0
-	MTMSR_EERI(r6)
-	mtsrr0	r9
-	mtsrr1	r4
 
 	PPC_LL	r0, SVCPU_R0(r3)
 	PPC_LL	r1, SVCPU_R1(r3)
 	PPC_LL	r2, SVCPU_R2(r3)
-	PPC_LL	r4, SVCPU_R4(r3)
 	PPC_LL	r5, SVCPU_R5(r3)
-	PPC_LL	r6, SVCPU_R6(r3)
 	PPC_LL	r7, SVCPU_R7(r3)
 	PPC_LL	r8, SVCPU_R8(r3)
-	PPC_LL	r9, SVCPU_R9(r3)
 	PPC_LL	r10, SVCPU_R10(r3)
 	PPC_LL	r11, SVCPU_R11(r3)
 	PPC_LL	r12, SVCPU_R12(r3)
 	PPC_LL	r13, SVCPU_R13(r3)
 
+	MTMSR_EERI(r6)
+	mtsrr0	r9
+	mtsrr1	r4
+
+	PPC_LL	r4, SVCPU_R4(r3)
+	PPC_LL	r6, SVCPU_R6(r3)
+	PPC_LL	r9, SVCPU_R9(r3)
 	PPC_LL	r3, (SVCPU_R3)(r3)
 
 	RFI