[PATCH v4 0/2] migration: Store ram size value

[Juan Quintela <quintela@redhat.com>]

Hi

Changes on this series:
- Address review by Philippe.
- Added review by.

Please review.

[v3]
This is just a rebase on top of latest upstream and make
scripts/checkpatch.pl happy.

Please, review.

[v2]
I just resized this patch for latest upstream, we still have the same
trouble for huge guests, we are doing lots of RCU operations that are
not needed at all.  As David explained on the previous submission,
ram_mig_ram_block_resized() aborts migration when size changes.

Please review.

[v1]

Current migration code recalculates the amount of RAM each time that
is needed.  This calculation requires RCU and other operations.
During migration we disable hot/unplug of memory, so we can store it.

Notice the times difference, and specially that ram_bytes_total()
don't appears anymore in the perf output.

total time: 75852 ms
downtime: 264 ms
setup: 273 ms
transferred ram: 19671939 kbytes
throughput: 2132.28 mbps
remaining ram: 0 kbytes
total ram: 1077936904 kbytes
duplicate: 265170289 pages
skipped: 0 pages
normal: 4316628 pages
normal bytes: 17266512 kbytes
dirty sync count: 4
page size: 4 kbytes
multifd bytes: 17341329 kbytes
pages-per-second: 1236658
precopy ram: 2330608 kbytes
downtime ram: 1 kbytes

  37.97%  live_migration   qemu-system-x86_64       [.] buffer_zero_avx512
  10.42%  live_migration   qemu-system-x86_64       [.] ram_find_and_save_block.part.0
   6.67%  live_migration   qemu-system-x86_64       [.] add_to_iovec
   3.71%  live_migration   qemu-system-x86_64       [.] ram_bytes_total_common
   2.79%  live_migration   qemu-system-x86_64       [.] qemu_ram_is_migratable
   2.69%  live_migration   qemu-system-x86_64       [.] qemu_put_byte.part.0
   2.41%  live_migration   qemu-system-x86_64       [.] bitmap_test_and_clear_atomic
   1.55%  live_migration   qemu-system-x86_64       [.] qemu_put_be32
   1.26%  live_migration   qemu-system-x86_64       [.] find_next_bit
   1.07%  multifdsend_0    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.07%  multifdsend_13   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.06%  multifdsend_6    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.05%  multifdsend_2    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.04%  multifdsend_15   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.03%  multifdsend_12   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.02%  live_migration   qemu-system-x86_64       [.] migrate_ignore_shared
   1.01%  multifdsend_7    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.01%  multifdsend_3    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   1.01%  multifdsend_10   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.98%  live_migration   qemu-system-x86_64       [.] ram_save_iterate
   0.96%  multifdsend_4    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.93%  multifdsend_8    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.92%  multifdsend_5    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.90%  multifdsend_14   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.88%  multifdsend_9    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.85%  multifdsend_1    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.83%  multifdsend_11   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.61%  live_migration   qemu-system-x86_64       [.] save_zero_page_to_file.part.0
   0.48%  live_migration   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string

Migration status: completed
total time: 70033 ms
downtime: 279 ms
setup: 280 ms
transferred ram: 19692747 kbytes
throughput: 2312.82 mbps
remaining ram: 0 kbytes
total ram: 1077936904 kbytes
duplicate: 265164421 pages
skipped: 0 pages
normal: 4322415 pages
normal bytes: 17289660 kbytes
dirty sync count: 3
page size: 4 kbytes
multifd bytes: 17362190 kbytes
pages-per-second: 2523447
precopy ram: 2330555 kbytes
downtime ram: 1 kbytes

  43.64%  live_migration   qemu-system-x86_64       [.] buffer_zero_avx512
  11.32%  live_migration   qemu-system-x86_64       [.] ram_find_and_save_block.part.0
   7.60%  live_migration   qemu-system-x86_64       [.] add_to_iovec
   2.95%  live_migration   qemu-system-x86_64       [.] qemu_put_byte.part.0
   2.73%  live_migration   qemu-system-x86_64       [.] bitmap_test_and_clear_atomic
   1.76%  live_migration   qemu-system-x86_64       [.] qemu_put_be32
   1.44%  live_migration   qemu-system-x86_64       [.] find_next_bit
   0.84%  multifdsend_1    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.84%  multifdsend_7    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.81%  multifdsend_15   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.80%  multifdsend_4    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.80%  multifdsend_3    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.79%  multifdsend_12   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.79%  multifdsend_14   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.79%  multifdsend_11   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.78%  multifdsend_13   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.78%  live_migration   qemu-system-x86_64       [.] ram_save_iterate
   0.77%  multifdsend_9    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.77%  multifdsend_5    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.77%  multifdsend_10   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.77%  multifdsend_2    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.77%  multifdsend_6    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.76%  multifdsend_8    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.71%  multifdsend_0    [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.66%  live_migration   qemu-system-x86_64       [.] save_zero_page_to_file.part.0
   0.62%  live_migration   qemu-system-x86_64       [.] qemu_ram_is_migratable
   0.54%  live_migration   [kernel.kallsyms]        [k] copy_user_enhanced_fast_string
   0.51%  live_migration   qemu-system-x86_64       [.] qemu_put_byte

Please, review.

Thanks, Juan.

Juan Quintela (2):
  migration: Split ram_bytes_total_common() in two functions
  migration: Calculate ram size once

 migration/ram.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

-- 
2.39.1