2010-07-07 11:12:45 +00:00
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From: Alexander Graf <agraf@suse.de>
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Date: Wed, 18 Nov 2009 12:58:00 +0100
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Subject: Replace kvm io delay pv-ops with linux magic
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References: bnc#556135, FATE#306453
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Patch-Mainline: Submitted to virtualization list
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Currently we use pv-ops to tell linux not to do anything on io_delay.
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While the basic idea is good IMHO, I don't see why we would need pv-ops
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for that. The io delay function already has a switch that can do nothing
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if you're so inclined.
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So here's a patch (stacked on top of the previous pv-ops series) that
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removes the io delay pv-ops hook and just sets the native io delay
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variable instead.
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Signed-off-by: Alexander Graf <agraf@suse.de>
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---
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arch/x86/Kconfig | 14 --------------
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arch/x86/kernel/kvm.c | 16 +++-------------
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2 files changed, 3 insertions(+), 27 deletions(-)
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--- a/arch/x86/Kconfig
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+++ b/arch/x86/Kconfig
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2011-04-19 20:09:59 +00:00
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@@ -548,20 +548,6 @@ config KVM_GUEST
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2010-07-07 11:12:45 +00:00
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This option enables various optimizations for running under the KVM
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hypervisor.
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-config KVM_IODELAY
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- bool "KVM IO-delay support"
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- depends on KVM_GUEST
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- select PARAVIRT_CPU
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- ---help---
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- Usually we wait for PIO access to complete. When inside KVM there's
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- no need to do that, as we know that we're not going through a bus,
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- but process PIO requests instantly.
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-
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- This option disables PIO waits, but drags in CPU-bound pv-ops. Thus
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- you will probably get more speed loss than speedup using this option.
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-
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- If in doubt, say N.
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-
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config KVM_MMU
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bool "KVM PV MMU support"
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depends on KVM_GUEST
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--- a/arch/x86/kernel/kvm.c
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+++ b/arch/x86/kernel/kvm.c
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@@ -29,15 +29,6 @@
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2011-04-19 20:09:59 +00:00
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#include <asm/desc.h>
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#include <asm/tlbflush.h>
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2010-07-07 11:12:45 +00:00
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-#ifdef CONFIG_KVM_IODELAY
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-/*
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- * No need for any "IO delay" on KVM
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- */
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-static void kvm_io_delay(void)
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-{
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-}
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-#endif /* CONFIG_KVM_IODELAY */
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-
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#ifdef CONFIG_KVM_MMU
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#define MMU_QUEUE_SIZE 1024
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@@ -201,13 +192,12 @@ static void kvm_leave_lazy_mmu(void)
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static void __init paravirt_ops_setup(void)
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{
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+ extern int io_delay_type;
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pv_info.name = "KVM";
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pv_info.paravirt_enabled = 1;
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-#ifdef CONFIG_KVM_IODELAY
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- if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
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- pv_cpu_ops.io_delay = kvm_io_delay;
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-#endif
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+ /* Disable IO delay */
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+ io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
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#ifdef CONFIG_KVM_MMU
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if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
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