From 27ff42e29a1d12e9d9dbc473bbca36a50baf278b Mon Sep 17 00:00:00 2001 From: Michael Chapman Date: Wed, 15 Apr 2015 13:59:14 +1000 Subject: migration: avoid divide by zero in xbzrle cache miss rate This bug manifested itself as a VM that could not be resumed by libvirt following a migration: # virsh resume example error: Failed to resume domain example error: internal error: cannot parse json {"return": {"xbzrle-cache": {..., "cache-miss-rate": -nan, ...}, ... } }: lexical error: malformed number, a digit is required after the minus sign. This patch also ensures xbzrle_cache_miss_prev and iterations_prev are cleared at the start of the migration. Signed-off-by: Michael Chapman Reviewed-by: Amit Shah Signed-off-by: Juan Quintela --- arch_init.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'arch_init.c') diff --git a/arch_init.c b/arch_init.c index 539011d2c6..bbf0031019 100644 --- a/arch_init.c +++ b/arch_init.c @@ -663,12 +663,16 @@ static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length) static int64_t start_time; static int64_t bytes_xfer_prev; static int64_t num_dirty_pages_period; +static uint64_t xbzrle_cache_miss_prev; +static uint64_t iterations_prev; static void migration_bitmap_sync_init(void) { start_time = 0; bytes_xfer_prev = 0; num_dirty_pages_period = 0; + xbzrle_cache_miss_prev = 0; + iterations_prev = 0; } /* Called with iothread lock held, to protect ram_list.dirty_memory[] */ @@ -679,8 +683,6 @@ static void migration_bitmap_sync(void) MigrationState *s = migrate_get_current(); int64_t end_time; int64_t bytes_xfer_now; - static uint64_t xbzrle_cache_miss_prev; - static uint64_t iterations_prev; bitmap_sync_count++; @@ -728,7 +730,7 @@ static void migration_bitmap_sync(void) mig_throttle_on = false; } if (migrate_use_xbzrle()) { - if (iterations_prev != 0) { + if (iterations_prev != acct_info.iterations) { acct_info.xbzrle_cache_miss_rate = (double)(acct_info.xbzrle_cache_miss - xbzrle_cache_miss_prev) / -- cgit v1.2.3