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From: Alexander Graf <agraf@suse.de>
To: kvm list <kvm@vger.kernel.org>
Cc: kvm-ppc <kvm-ppc@vger.kernel.org>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: [PATCH 2/2] KVM: PPC: Book3S: PR: No isync in slbie path
Date: Wed, 25 Apr 2012 12:38:22 +0000	[thread overview]
Message-ID: <1335357502-30113-2-git-send-email-agraf@suse.de> (raw)
In-Reply-To: <1335357502-30113-1-git-send-email-agraf@suse.de>

While messing around with the SLBs we're running in real mode. The
entry to guest space goes through rfid, which is context synchronizing,
so there's no need to manually synchronize anything through isync.

With this patch and a simple priviledged SPR access loop guest, I get
a speed bump from 2035607 to 2181301 exits per second.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/kvm/book3s_64_slb.S |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_slb.S b/arch/powerpc/kvm/book3s_64_slb.S
index f2e6e48..56b983e 100644
--- a/arch/powerpc/kvm/book3s_64_slb.S
+++ b/arch/powerpc/kvm/book3s_64_slb.S
@@ -90,8 +90,6 @@ slb_exit_skip_ ## num:
 	or      r10, r10, r12
 	slbie	r10
 
-	isync
-
 	/* Fill SLB with our shadow */
 
 	lbz	r12, SVCPU_SLB_MAX(r3)
-- 
1.6.0.2


      reply	other threads:[~2012-04-25 12:38 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-25 12:38 [PATCH 1/2] KVM: PPC: Book3S: PR: Optimize entry path Alexander Graf
2012-04-25 12:38 ` Alexander Graf [this message]

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