| Message ID | 1616639091-28279-9-git-send-email-lei.rao@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fixed some bugs and optimized some codes for COLO | expand |
* leirao (lei.rao@intel.com) wrote: > From: "Rao, Lei" <lei.rao@intel.com> > > When flushing memory from ram cache to ram during every checkpoint > on secondary VM, we can copy continuous chunks of memory instead of > 4096 bytes per time to reduce the time of VM stop during checkpoint. > > Signed-off-by: Lei Rao <lei.rao@intel.com> A minor comment below, but : Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > migration/ram.c | 45 ++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 42 insertions(+), 3 deletions(-) > > diff --git a/migration/ram.c b/migration/ram.c > index c69a8e0..a258466 100644 > --- a/migration/ram.c > +++ b/migration/ram.c > @@ -822,6 +822,39 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, > return next; > } > > +/* > + * colo_bitmap_find_diry:find contiguous dirty pages from start > + * > + * Returns the page offset within memory region of the start of the contiguout > + * dirty page > + * > + * @rs: current RAM state > + * @rb: RAMBlock where to search for dirty pages > + * @start: page where we start the search > + * @num: the number of contiguous dirty pages > + */ > +static inline > +unsigned long colo_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, > + unsigned long start, unsigned long *num) > +{ > + unsigned long size = rb->used_length >> TARGET_PAGE_BITS; > + unsigned long *bitmap = rb->bmap; > + unsigned long first, next; It might be better to add the *num = 0 here, which means this function always writes num > + if (ramblock_is_ignored(rb)) { > + return size; > + } > + > + first = find_next_bit(bitmap, size, start); > + if (first >= size) { > + return first; > + } > + next = find_next_zero_bit(bitmap, size, first + 1); > + assert(next >= first); > + *num = next - first; > + return first; > +} > + > static inline bool migration_bitmap_clear_dirty(RAMState *rs, > RAMBlock *rb, > unsigned long page) > @@ -3666,6 +3699,8 @@ void colo_flush_ram_cache(void) > void *dst_host; > void *src_host; > unsigned long offset = 0; > + unsigned long num = 0; that could move inside the while loop. > + unsigned long i = 0; This line could move inside the 'else' clause below that uses it. > memory_global_dirty_log_sync(); > WITH_RCU_READ_LOCK_GUARD() { > @@ -3679,19 +3714,23 @@ void colo_flush_ram_cache(void) > block = QLIST_FIRST_RCU(&ram_list.blocks); > > while (block) { > - offset = migration_bitmap_find_dirty(ram_state, block, offset); > + offset = colo_bitmap_find_dirty(ram_state, block, offset, &num); > > if (((ram_addr_t)offset) << TARGET_PAGE_BITS > >= block->used_length) { > offset = 0; > + num = 0; > block = QLIST_NEXT_RCU(block, next); > } else { > - migration_bitmap_clear_dirty(ram_state, block, offset); > + for (i = 0; i < num; i++) { > + migration_bitmap_clear_dirty(ram_state, block, offset + i); > + } > dst_host = block->host > + (((ram_addr_t)offset) << TARGET_PAGE_BITS); > src_host = block->colo_cache > + (((ram_addr_t)offset) << TARGET_PAGE_BITS); > - memcpy(dst_host, src_host, TARGET_PAGE_SIZE); > + memcpy(dst_host, src_host, TARGET_PAGE_SIZE * num); > + offset += num; I was initially confused as to why the old code didn't have an offset++ but I guess that means it just checked the bit a second time that was just cleared. Dave > } > } > } > -- > 1.8.3.1 >
diff --git a/migration/ram.c b/migration/ram.c index c69a8e0..a258466 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -822,6 +822,39 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, return next; } +/* + * colo_bitmap_find_diry:find contiguous dirty pages from start + * + * Returns the page offset within memory region of the start of the contiguout + * dirty page + * + * @rs: current RAM state + * @rb: RAMBlock where to search for dirty pages + * @start: page where we start the search + * @num: the number of contiguous dirty pages + */ +static inline +unsigned long colo_bitmap_find_dirty(RAMState *rs, RAMBlock *rb, + unsigned long start, unsigned long *num) +{ + unsigned long size = rb->used_length >> TARGET_PAGE_BITS; + unsigned long *bitmap = rb->bmap; + unsigned long first, next; + + if (ramblock_is_ignored(rb)) { + return size; + } + + first = find_next_bit(bitmap, size, start); + if (first >= size) { + return first; + } + next = find_next_zero_bit(bitmap, size, first + 1); + assert(next >= first); + *num = next - first; + return first; +} + static inline bool migration_bitmap_clear_dirty(RAMState *rs, RAMBlock *rb, unsigned long page) @@ -3666,6 +3699,8 @@ void colo_flush_ram_cache(void) void *dst_host; void *src_host; unsigned long offset = 0; + unsigned long num = 0; + unsigned long i = 0; memory_global_dirty_log_sync(); WITH_RCU_READ_LOCK_GUARD() { @@ -3679,19 +3714,23 @@ void colo_flush_ram_cache(void) block = QLIST_FIRST_RCU(&ram_list.blocks); while (block) { - offset = migration_bitmap_find_dirty(ram_state, block, offset); + offset = colo_bitmap_find_dirty(ram_state, block, offset, &num); if (((ram_addr_t)offset) << TARGET_PAGE_BITS >= block->used_length) { offset = 0; + num = 0; block = QLIST_NEXT_RCU(block, next); } else { - migration_bitmap_clear_dirty(ram_state, block, offset); + for (i = 0; i < num; i++) { + migration_bitmap_clear_dirty(ram_state, block, offset + i); + } dst_host = block->host + (((ram_addr_t)offset) << TARGET_PAGE_BITS); src_host = block->colo_cache + (((ram_addr_t)offset) << TARGET_PAGE_BITS); - memcpy(dst_host, src_host, TARGET_PAGE_SIZE); + memcpy(dst_host, src_host, TARGET_PAGE_SIZE * num); + offset += num; } } }