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[Qemu-devel] [PATCHv5 00/10] buffer_is_zero / migration optimizations
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [PATCHv5 00/10] buffer_is_zero / migration optimizations |
Date: |
Tue, 26 Mar 2013 10:58:29 +0100 |
this is v5 of my patch series with various optimizations in
zero buffer checking and migration tweaks.
thanks especially to Eric Blake, Orit Wassermann and Paolo Bonzini
for reviewing.
v5:
- move zero splat vector to a different patch
- fix indentation of can_user_buffer_find_nonzero_offset()
- do not unroll the first loop in buffer_find_nonzero_offset()
to optimize it for zero page checking
- use an older unrolled version of find_next_bit() without
SIMD instruction as there is no evidence that the vectorized
version is better if not even worse and the code is easier
to understand.
- added a word in the commit message of patch 8
about the skipped pages field in QMP MigrationStats.
- fixed the order of key-value pairs of MigrationStats in
qapi-schema.json
- updated info about the performance benefit of is_zero_page()
to the latest benchmark results in the commit message.
v4:
- do not inline buffer_find_nonzero_offset()
- inline can_usebuffer_find_nonzero_offset() correctly
- readd asserts in buffer_find_nonzero_offset() as profiling
shows they do not hurt.
- change last occurences of scalar 8 by
BUFFER_FIND_NONZERO_OFFSET_UNROLL_FACTOR
- avoid deferencing p already in patch 5 where we
know that the page (p) is zero
- explicitly set bytes_sent = 0 if we skip a zero page.
bytes_sent was 0 before, but it was not obvious.
- add accounting information for skipped zero pages
- fix errors reported by checkpatch.pl
v3:
- remove asserts, inline functions and add a check
function if buffer_find_nonzero_offset() can be used.
- use above check function in buffer_is_zero() and
find_next_bit().
- use buffer_is_nonzero_offset() directly to find
zero pages. we know that all requirements are met
for memory pages.
- fix C89 violation in buffer_is_zero().
- avoid derefencing p in ram_save_block() if we already
know the page is zero.
- fix initialization of last_offset in reset_ram_globals().
- avoid skipping pages with offset == 0 in bulk stage in
migration_bitmap_find_and_reset_dirty().
- compared to v1 check for zero pages also after bulk
ram migration as there are guests (e.g. Windows) which
zero out large amount of memory while running.
v2:
- fix description, add trivial zero check and add asserts
to buffer_find_nonzero_offset.
- add a constant for the unroll factor of buffer_find_nonzero_offset
- replace is_dup_page() by buffer_is_zero()
- added test results to xbzrle patch
- optimize descriptions
Peter Lieven (10):
move vector definitions to qemu-common.h
add a zero splat vector to qemu-common.h
cutils: add a function to find non-zero content in a buffer
buffer_is_zero: use vector optimizations if possible
bitops: unroll while loop in find_next_bit()
migration: search for zero instead of dup pages
migration: add an indicator for bulk state of ram migration
migration: do not sent zero pages in bulk stage
migration: do not search dirty pages in bulk stage
migration: use XBZRLE only after bulk stage
arch_init.c | 74 +++++++++++++++++++----------------------
hmp.c | 2 ++
include/migration/migration.h | 2 ++
include/qemu-common.h | 37 +++++++++++++++++++++
migration.c | 3 +-
qapi-schema.json | 8 +++--
qmp-commands.hx | 3 +-
util/bitops.c | 18 +++++++++-
util/cutils.c | 60 +++++++++++++++++++++++++++++++++
9 files changed, 162 insertions(+), 45 deletions(-)
--
1.7.9.5
- [Qemu-devel] [PATCHv5 00/10] buffer_is_zero / migration optimizations,
Peter Lieven <=
- [Qemu-devel] [PATCHv5 04/10] buffer_is_zero: use vector optimizations if possible, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 05/10] bitops: unroll while loop in find_next_bit(), Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 08/10] migration: do not sent zero pages in bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 09/10] migration: do not search dirty pages in bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 07/10] migration: add an indicator for bulk state of ram migration, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 06/10] migration: search for zero instead of dup pages, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 10/10] migration: use XBZRLE only after bulk stage, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 01/10] move vector definitions to qemu-common.h, Peter Lieven, 2013/03/26
- [Qemu-devel] [PATCHv5 02/10] add a zero splat vector to qemu-common.h, Peter Lieven, 2013/03/26