[Qemu-arm] [RFC PATCH v2 0/2] Live migration optimization for Thunderx platform

[vijay . kilari]

From: Vijaya Kumar K <address@hidden>

The CPU MIDR_EL1 register is exposed to userspace for arm64
with the below patch.
https://lkml.org/lkml/2016/7/8/467

Thunderx platform requires explicit prefetch instruction to
provide prefetch hint. Using MIDR_EL1 information, provided
by above kernel patch, prefetch is executed if the platform
is Thunderx.

The results of live migration time improvement is provided
in commit message of patch 2.

Note: Check for size of while prefetching beyond page is
not added. Making this check is counter productive on
performance of live migration.

v1 => v2:
   - Rename util/cpuinfo.c as util/aarch64-cpuid.c
   - Introduced header file include/qemu/aarch64-cpuid.h
   - Place all arch specific code under define __aarch64__ and
     CONFIG_LINUX.
   - Used builtin_prefetch() to add prefetch instruction.
   - Moved arch specific changes out of generic code
   - Dropped prefetching 5th cache line.

Vijaya Kumar K (2):
  utils: Add helper to read arm MIDR_EL1 register
  utils: Add prefetch for Thunderx platform

 include/qemu/aarch64-cpuid.h |  9 +++++
 util/Makefile.objs           |  1 +
 util/aarch64-cpuid.c         | 94 ++++++++++++++++++++++++++++++++++++++++++++
 util/cutils.c                | 31 +++++++++++++++
 4 files changed, 135 insertions(+)
 create mode 100644 include/qemu/aarch64-cpuid.h
 create mode 100644 util/aarch64-cpuid.c

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1.9.1