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Message-Id: <1399400175-23754-1-git-send-email-pbonzini@redhat.com>
Date: Tue, 6 May 2014 20:16:11 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: kvm@...r.kernel.org, bsd@...hat.com
Subject: [RFC PATCH 0/4] KVM: emulator: speed up instruction fetch
This small series provides another ~6% speedup on top of Bandan's patches.
It does so by speeding up instruction fetches. The three tricks, one per
patch, are to help the compiler a bit by redistributing the work between
do_insn_fetch_byte and do_insn_fetch, to avoid repeated checks on the
boundary of the fetch cache, and to exploit the processor's support for
unaligned accesses.
Before:
819 cycles/emulated jump instruction
1020 cycles/emulated move instruction
1026 cycles/emulated arithmetic instruction
1264 cycles/emulated memory load instruction
1182 cycles/emulated memory store instruction
1299 cycles/emulated memory RMW instruction
After:
771 cycles/emulated jump instruction
963 cycles/emulated move instruction
960 cycles/emulated arithmetic instruction
1192 cycles/emulated memory load instruction
1110 cycles/emulated memory store instruction
1228 cycles/emulated memory RMW instruction
Paolo Bonzini (4):
KVM: emulate: speed up do_insn_fetch
KVM: emulate: avoid repeated calls to do_insn_fetch_bytes
KVM: emulate: avoid per-byte copying in instruction fetches
KVM: emulate: put pointers in the fetch_cache
arch/x86/include/asm/kvm_emulate.h | 4 +-
arch/x86/kvm/emulate.c | 97 ++++++++++++++++++++------------------
arch/x86/kvm/trace.h | 6 +--
3 files changed, 57 insertions(+), 50 deletions(-)
--
1.8.3.1
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