Hi
This series split the dirty bitmap (8 bits per page, only three used)
into 3 individual bitmaps. Once the conversion is done, operations
are handled by bitmap operations, not bit by bit.
- *_DIRTY_FLAG flags are gone, now we use memory.h DIRTY_MEMORY_*
everywhere.
- We set/reset each flag individually
(set_dirty_flags(0xff&~CODE_DIRTY_FLAG)) are gone.
- Rename several functions to clarify/make consistent things.
- I know it dont't pass checkpatch for long lines, propper submission
should pass it. We have to have long lines, short variable names, or
ugly line splitting :p
- DIRTY_MEMORY_NUM: how can one include exec/memory.h into cpu-all.h?
#include it don't work, as a workaround, I have copied its value, but
any better idea? I can always create "exec/migration-flags.h", though.
- The meat of the code is patch 19. Rest of patches are quite easy
(even that one is not too complex).
Only optimizations done so far are
set_dirty_range()/clear_dirty_range() that now operates with
bitmap_set/clear.
Note for Xen: cpu_physical_memory_set_dirty_range() was wrong for xen,
see comment on patch.
It passes virt-test migration tests, so it should be perfect.
I post it to ask for comments.
ToDo list:
- create a lock for the bitmaps and fold migration bitmap into this
one. This would avoid a copy and make things easier?
- As this code uses/abuses bitmaps, we need to change the type of the
index from int to long. With an int index, we can only access a
maximum of 8TB guest (yes, this is not urgent, we have a couple of
years to do it).
- merging KVM <-> QEMU bitmap as a bitmap and not bit-by-bit.
- spliting the KVM bitmap synchronization into chunks, i.e. not
synchronize all memory, just enough to continue with migration.
Any further ideas/needs?
Thanks, Juan.
PD. Why it took so long?
Because I was trying to integrate the bitmap on the MemoryRegion
abstraction. Would have make the code cleaner, but hit dead-end
after dead-end. As practical terms, TCG don't know about
MemoryRegions, it has been ported to run on top of them, but
don't use them effectively.
The following changes since commit a684f3cf9b9b9c3cb82be87aafc463de8974610c:
Merge remote-tracking branch 'kraxel/seabios-1.7.3.2' into staging
(2013-09-30 17:15:27 -0500)
are available in the git repository at:
git://github.com/juanquintela/qemu.git bitmap.next
for you to fetch changes up to a90a941c24589d618b3d8461675d9b5afb3288cb:
memory: cpu_physical_memory_clear_dirty_range() now uses bitmap operations
(2013-10-09 12:30:35 +0200)
----------------------------------------------------------------
Juan Quintela (28):
Move prototypes to memory.h
memory: cpu_physical_memory_set_dirty_flags() result is never used
memory: cpu_physical_memory_set_dirty_range() return void
exec: use accessor function to know if memory is dirty
memory: create function to set a single dirty bit
exec: create function to get a single dirty bit
memory: make cpu_physical_memory_is_dirty return bool
exec: simplify notdirty_mem_write()
memory: all users of cpu_physical_memory_get_dirty used only one flag
memory: set single dirty flags when possible
memory: cpu_physical_memory_set_dirty_range() allways dirty all flags
memory: cpu_physical_memory_mask_dirty_range() allways clear a single flag
memory: use DIRTY_MEMORY_* instead of *_DIRTY_FLAG
memory: use bit 2 for migration
memory: make sure that client is always inside range
memory: only resize dirty bitmap when memory size increases
memory: cpu_physical_memory_clear_dirty_flag() result is never used
bitmap: Add bitmap_zero_extend operation
memory: split dirty bitmap into three
memory: unfold cpu_physical_memory_clear_dirty_flag() in its only user
memory: unfold cpu_physical_memory_set_dirty() in its only user
memory: unfold cpu_physical_memory_set_dirty_flag()
memory: make cpu_physical_memory_get_dirty() the main function
memory: cpu_physical_memory_get_dirty() is used as returning a bool
memory: s/mask/clear/ cpu_physical_memory_mask_dirty_range
memory: use find_next_bit() to find dirty bits
memory: cpu_physical_memory_set_dirty_range() now uses bitmap operations
memory: cpu_physical_memory_clear_dirty_range() now uses bitmap operations
cputlb.c | 4 +-
exec.c | 41 ++++++++++--------
include/exec/cpu-all.h | 4 +-
include/exec/cpu-common.h | 4 --
include/exec/memory-internal.h | 94 ++++++++++++++++++------------------------
include/exec/memory.h | 10 ++---
include/qemu/bitmap.h | 9 ++++
memory.c | 12 +++---
8 files changed, 88 insertions(+), 90 deletions(-)
