diff options
| -rw-r--r-- | block-migration.c | 32 | ||||
| -rw-r--r-- | include/migration/migration.h | 1 | ||||
| -rw-r--r-- | migration.c | 9 | ||||
| -rw-r--r-- | qapi-schema.json | 8 |
4 files changed, 43 insertions, 7 deletions
diff --git a/block-migration.c b/block-migration.c index 2fd7699794..f803f2006f 100644 --- a/block-migration.c +++ b/block-migration.c @@ -29,6 +29,7 @@ #define BLK_MIG_FLAG_DEVICE_BLOCK 0x01 #define BLK_MIG_FLAG_EOS 0x02 #define BLK_MIG_FLAG_PROGRESS 0x04 +#define BLK_MIG_FLAG_ZERO_BLOCK 0x08 #define MAX_IS_ALLOCATED_SEARCH 65536 @@ -80,6 +81,7 @@ typedef struct BlkMigState { int shared_base; QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list; int64_t total_sector_sum; + bool zero_blocks; /* Protected by lock. */ QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list; @@ -114,16 +116,30 @@ static void blk_mig_unlock(void) static void blk_send(QEMUFile *f, BlkMigBlock * blk) { int len; + uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK; + + if (block_mig_state.zero_blocks && + buffer_is_zero(blk->buf, BLOCK_SIZE)) { + flags |= BLK_MIG_FLAG_ZERO_BLOCK; + } /* sector number and flags */ qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS) - | BLK_MIG_FLAG_DEVICE_BLOCK); + | flags); /* device name */ len = strlen(blk->bmds->bs->device_name); qemu_put_byte(f, len); qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len); + /* if a block is zero we need to flush here since the network + * bandwidth is now a lot higher than the storage device bandwidth. + * thus if we queue zero blocks we slow down the migration */ + if (flags & BLK_MIG_FLAG_ZERO_BLOCK) { + qemu_fflush(f); + return; + } + qemu_put_buffer(f, blk->buf, BLOCK_SIZE); } @@ -344,6 +360,7 @@ static void init_blk_migration(QEMUFile *f) block_mig_state.total_sector_sum = 0; block_mig_state.prev_progress = -1; block_mig_state.bulk_completed = 0; + block_mig_state.zero_blocks = migrate_zero_blocks(); bdrv_iterate(init_blk_migration_it, NULL); } @@ -762,12 +779,15 @@ static int block_load(QEMUFile *f, void *opaque, int version_id) nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK; } - buf = g_malloc(BLOCK_SIZE); - - qemu_get_buffer(f, buf, BLOCK_SIZE); - ret = bdrv_write(bs, addr, buf, nr_sectors); + if (flags & BLK_MIG_FLAG_ZERO_BLOCK) { + ret = bdrv_write_zeroes(bs, addr, nr_sectors); + } else { + buf = g_malloc(BLOCK_SIZE); + qemu_get_buffer(f, buf, BLOCK_SIZE); + ret = bdrv_write(bs, addr, buf, nr_sectors); + g_free(buf); + } - g_free(buf); if (ret < 0) { return ret; } diff --git a/include/migration/migration.h b/include/migration/migration.h index bc9fde0b2a..701709a1e9 100644 --- a/include/migration/migration.h +++ b/include/migration/migration.h @@ -124,6 +124,7 @@ void migrate_add_blocker(Error *reason); void migrate_del_blocker(Error *reason); bool migrate_rdma_pin_all(void); +bool migrate_zero_blocks(void); bool migrate_auto_converge(void); diff --git a/migration.c b/migration.c index 9f5a4230d1..a9c042186d 100644 --- a/migration.c +++ b/migration.c @@ -493,6 +493,15 @@ bool migrate_auto_converge(void) return s->enabled_capabilities[MIGRATION_CAPABILITY_AUTO_CONVERGE]; } +bool migrate_zero_blocks(void) +{ + MigrationState *s; + + s = migrate_get_current(); + + return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS]; +} + int migrate_use_xbzrle(void) { MigrationState *s; diff --git a/qapi-schema.json b/qapi-schema.json index 8d33d527d3..592bb9c7a1 100644 --- a/qapi-schema.json +++ b/qapi-schema.json @@ -613,10 +613,16 @@ # Disabled by default. Experimental: may (or may not) be renamed after # further testing is complete. (since 1.6) # +# @zero-blocks: During storage migration encode blocks of zeroes efficiently. This +# essentially saves 1MB of zeroes per block on the wire. Enabling requires +# source and target VM to support this feature. To enable it is sufficient +# to enable the capability on the source VM. The feature is disabled by +# default. (since 1.6) +# # Since: 1.2 ## { 'enum': 'MigrationCapability', - 'data': ['xbzrle', 'x-rdma-pin-all', 'auto-converge'] } + 'data': ['xbzrle', 'x-rdma-pin-all', 'auto-converge', 'zero-blocks'] } ## # @MigrationCapabilityStatus |