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Re: [Qemu-devel] [PULL 5/5] migratioin/ram: leave RAMBlock->bmap blank o
From: |
Wei Yang |
Subject: |
Re: [Qemu-devel] [PULL 5/5] migratioin/ram: leave RAMBlock->bmap blank on allocating |
Date: |
Wed, 5 Jun 2019 13:37:22 +0000 |
User-agent: |
NeoMutt/20170113 (1.7.2) |
On Wed, Jun 05, 2019 at 01:53:18PM +0200, Juan Quintela wrote:
>From: Wei Yang <address@hidden>
>
>During migration, we would sync bitmap from ram_list.dirty_memory to
>RAMBlock.bmap in cpu_physical_memory_sync_dirty_bitmap().
>
>Since we set RAMBlock.bmap and ram_list.dirty_memory both to all 1, this
>means at the first round this sync is meaningless and is a duplicated
>work.
>
>Leaving RAMBlock->bmap blank on allocating would have a side effect on
>migration_dirty_pages, since it is calculated from the result of
>cpu_physical_memory_sync_dirty_bitmap(). To keep it right, we need to
>set migration_dirty_pages to 0 in ram_state_init().
>
>Signed-off-by: Wei Yang <address@hidden>
>Reviewed-by: Dr. David Alan Gilbert <address@hidden>
>Reviewed-by: Juan Quintela <address@hidden>
>Signed-off-by: Juan Quintela <address@hidden>
I think Peter acked this and gave some suggestions.
>---
> migration/ram.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
>diff --git a/migration/ram.c b/migration/ram.c
>index 03a9cce9f9..082aea9d23 100644
>--- a/migration/ram.c
>+++ b/migration/ram.c
>@@ -3173,11 +3173,11 @@ static int ram_state_init(RAMState **rsp)
> QSIMPLEQ_INIT(&(*rsp)->src_page_requests);
>
> /*
>- * Count the total number of pages used by ram blocks not including any
>- * gaps due to alignment or unplugs.
>+ * This must match with the initial values of dirty bitmap.
>+ * Currently we initialize the dirty bitmap to all zeros so
>+ * here the total dirty page count is zero.
> */
>- (*rsp)->migration_dirty_pages = ram_bytes_total() >> TARGET_PAGE_BITS;
>-
>+ (*rsp)->migration_dirty_pages = 0;
> ram_state_reset(*rsp);
>
> return 0;
>@@ -3192,8 +3192,16 @@ static void ram_list_init_bitmaps(void)
> if (ram_bytes_total()) {
> RAMBLOCK_FOREACH_NOT_IGNORED(block) {
> pages = block->max_length >> TARGET_PAGE_BITS;
>+ /*
>+ * The initial dirty bitmap for migration must be set with all
>+ * ones to make sure we'll migrate every guest RAM page to
>+ * destination.
>+ * Here we didn't set RAMBlock.bmap simply because it is already
>+ * set in ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION] in
>+ * ram_block_add, and that's where we'll sync the dirty bitmaps.
>+ * Here setting RAMBlock.bmap would be fine too but not necessary.
>+ */
> block->bmap = bitmap_new(pages);
>- bitmap_set(block->bmap, 0, pages);
> if (migrate_postcopy_ram()) {
> block->unsentmap = bitmap_new(pages);
> bitmap_set(block->unsentmap, 0, pages);
>--
>2.21.0
>
--
Wei Yang
Help you, Help me
- [Qemu-devel] [PULL 0/5] Migration patches, Juan Quintela, 2019/06/05
- [Qemu-devel] [PULL 1/5] migration/ram.c: MultiFDSendParams.sem_sync is not really used, Juan Quintela, 2019/06/05
- [Qemu-devel] [PULL 2/5] migration/ram.c: multifd_send_state->count is not really used, Juan Quintela, 2019/06/05
- [Qemu-devel] [PULL 5/5] migratioin/ram: leave RAMBlock->bmap blank on allocating, Juan Quintela, 2019/06/05
- [Qemu-devel] [PULL 3/5] migration: Fix fd protocol for incoming defer, Juan Quintela, 2019/06/05
- [Qemu-devel] [PULL 4/5] migration-test: Add a test for fd protocol, Juan Quintela, 2019/06/05
- Re: [Qemu-devel] [PULL 0/5] Migration patches, Peter Maydell, 2019/06/06