linux-kernel - Re: [RFC PATCH 0/6] KVM: x86: speedups for emulator memory accesses

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Date:	Mon, 21 Apr 2014 17:12:56 -0300
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [RFC PATCH 0/6] KVM: x86: speedups for emulator memory accesses

On Tue, Apr 01, 2014 at 05:26:40PM +0200, Paolo Bonzini wrote:
> Another emulator speedup series, shaving up to 400 cycles (25%) off
> RMW instructions.
> 
> The performance of various instructions is now relatively flat:
> 
>  jump  919  (down from 2300)
>  move  1075 (down from 2700)
>  arith 1081 (down from 2600)
>  load  1267 (down from 2800, 1400 after previous round)
>  store 1213 (down from 2900, 1300 after previous round)
>  RMW   1310 (down from 3200, 1700 after previous round)
> 
> The next low-hanging fruit is fetching instructions and initializing
> the context.  Similar optimizations to those done here could be made
> for instruction fetch.
> 
> Paolo Bonzini (6):
>   KVM: emulate: simplify writeback
>   KVM: emulate: abstract handling of memory operands
>   KVM: export mark_page_dirty_in_slot
>   KVM: emulate: introduce memory_prepare callback to speed up memory access
>   KVM: emulate: activate memory access optimization
>   KVM: emulate: extend memory access optimization to stores
> 
>  arch/x86/include/asm/kvm_emulate.h |  28 ++++++++++
>  arch/x86/kvm/emulate.c             | 107 +++++++++++++++++++++++++++----------
>  arch/x86/kvm/x86.c                 |  67 +++++++++++++++++++++++
>  include/linux/kvm_host.h           |   6 +++
>  virt/kvm/kvm_main.c                |  17 ++----
>  5 files changed, 185 insertions(+), 40 deletions(-)
> 
> -- 
> 1.8.3.1

Reviewed-by: Marcelo Tosatti <mtosatti@...hat.com>

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