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[Qemu-devel] [PATCH 00/22] Dirty bitmap atomic access and optimizations
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 00/22] Dirty bitmap atomic access and optimizations |
Date: |
Thu, 26 Mar 2015 18:38:18 +0100 |
QEMU is currently accessing the dirty bitmaps very liberally,
which is understandable since the accesses are cheap. This is
however not good for squeezing maximum performance out of dataplane,
and is also not good if the accesses become more expensive---as is
the case when they use atomic primitives.
Patches 1-2 make acpi-build.h only use public memory APIs.
Patches 3-7 optimize access to the VGA dirty bitmap, by restricting
it to video RAM only.
Patches 8-15 optimize access to the code and migration bitmaps,
by tracking them respectively if TCG is enabled and if migration
is in progress. Note that the first iteration of migration already
does not look at the migration bitmap (commit 70c8652, migration:
do not search dirty pages in bulk stage, 2013-03-26).
Patches 16-21 are Stefan's patches to convert bitmap access to use
atomic primitives.
While the main purpose of these patches is a working dirty bitmap
for dataplane (and possibly multithreaded TCG), there's something
that they are immediately useful for: patch 22 makes the migration
thread synchronize the bitmap outside the big QEMU lock, thus
removing the last source of jitter during the RAM copy phase of
migration.
Please review and test! (it's available as branch "atomic-dirty"
on my github repository) In particular, I suspect that the
postcopy patches might be good at finding bugs.
Paolo
Paolo Bonzini (16):
memory: add memory_region_ram_resize
acpi-build: remove dependency from ram_addr.h
memory: the only dirty memory flag for users is DIRTY_MEMORY_VGA
display: enable DIRTY_MEMORY_VGA tracking explicitly
memory: return bitmap from memory_region_is_logging
framebuffer: check memory_region_is_logging
ui/console: check memory_region_is_logging
memory: track DIRTY_MEMORY_CODE in mr->dirty_log_mask
memory: return DIRTY_MEMORY_MIGRATION from memory_region_is_logging
ram_addr: tweaks to xen_modified_memory
exec: simplify notdirty_mem_write
exec: use memory_region_is_logging to optimize dirty tracking
exec: pass client mask to cpu_physical_memory_set_dirty_range
exec: only check relevant bitmaps for cleanliness
memory: do not touch code dirty bitmap unless TCG is enabled
migration: run bitmap sync outside iothread lock
Stefan Hajnoczi (6):
bitmap: add atomic set functions
bitmap: add atomic test and clear
memory: use atomic ops for setting dirty memory bits
migration: move dirty bitmap sync to ram_addr.h
memory: replace cpu_physical_memory_reset_dirty() with test-and-clear
memory: make cpu_physical_memory_sync_dirty_bitmap() fully atomic
arch_init.c | 56 +++----------------
cputlb.c | 4 +-
exec.c | 103 ++++++++++++++++------------------
hw/core/loader.c | 8 +--
hw/display/cg3.c | 1 +
hw/display/exynos4210_fimd.c | 7 ++-
hw/display/framebuffer.c | 23 ++++++--
hw/display/g364fb.c | 2 +-
hw/display/sm501.c | 1 +
hw/display/tcx.c | 1 +
hw/display/vmware_vga.c | 2 +-
hw/i386/acpi-build.c | 36 ++++++------
hw/virtio/vhost.c | 3 +-
include/exec/memory.h | 27 +++++++--
include/exec/ram_addr.h | 128 ++++++++++++++++++++++++++++---------------
include/hw/loader.h | 8 ++-
include/qemu/bitmap.h | 4 ++
include/qemu/bitops.h | 14 +++++
kvm-all.c | 3 +-
memory.c | 34 ++++++++----
ui/console.c | 14 +++--
util/bitmap.c | 78 ++++++++++++++++++++++++++
xen-hvm.c | 3 +-
23 files changed, 356 insertions(+), 204 deletions(-)
--
2.3.3
- [Qemu-devel] [PATCH 00/22] Dirty bitmap atomic access and optimizations,
Paolo Bonzini <=
- [Qemu-devel] [PATCH 01/22] memory: add memory_region_ram_resize, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 02/22] acpi-build: remove dependency from ram_addr.h, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 03/22] memory: the only dirty memory flag for users is DIRTY_MEMORY_VGA, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 04/22] display: enable DIRTY_MEMORY_VGA tracking explicitly, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 07/22] ui/console: check memory_region_is_logging, Paolo Bonzini, 2015/03/26
- [Qemu-devel] [PATCH 05/22] memory: return bitmap from memory_region_is_logging, Paolo Bonzini, 2015/03/26