From 3fc250b4be58cac2e392d8d01949f9e8471c36f9 Mon Sep 17 00:00:00 2001 From: Pierre Riteau Date: Wed, 12 May 2010 15:12:44 +0200 Subject: [PATCH] migration: Fix calculation of bytes_transferred When a page with all identical bytes is transferred, it is counted as a full page (TARGET_PAGE_SIZE) although only one byte is actually sent. Fix this by changing ram_save_block() to return the number of bytes sent instead of a boolean value. This makes bandwidth estimation, and consequently downtime estimation, more precise. Signed-off-by: Pierre Riteau Signed-off-by: Anthony Liguori --- arch_init.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/arch_init.c b/arch_init.c index cfc03ead53..8e849a885e 100644 --- a/arch_init.c +++ b/arch_init.c @@ -108,7 +108,7 @@ static int ram_save_block(QEMUFile *f) static ram_addr_t current_addr = 0; ram_addr_t saved_addr = current_addr; ram_addr_t addr = 0; - int found = 0; + int bytes_sent = 0; while (addr < last_ram_offset) { if (cpu_physical_memory_get_dirty(current_addr, MIGRATION_DIRTY_FLAG)) { @@ -123,19 +123,20 @@ static int ram_save_block(QEMUFile *f) if (is_dup_page(p, *p)) { qemu_put_be64(f, current_addr | RAM_SAVE_FLAG_COMPRESS); qemu_put_byte(f, *p); + bytes_sent = 1; } else { qemu_put_be64(f, current_addr | RAM_SAVE_FLAG_PAGE); qemu_put_buffer(f, p, TARGET_PAGE_SIZE); + bytes_sent = TARGET_PAGE_SIZE; } - found = 1; break; } addr += TARGET_PAGE_SIZE; current_addr = (saved_addr + addr) % last_ram_offset; } - return found; + return bytes_sent; } static uint64_t bytes_transferred; @@ -206,11 +207,11 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque) bwidth = qemu_get_clock_ns(rt_clock); while (!qemu_file_rate_limit(f)) { - int ret; + int bytes_sent; - ret = ram_save_block(f); - bytes_transferred += ret * TARGET_PAGE_SIZE; - if (ret == 0) { /* no more blocks */ + bytes_sent = ram_save_block(f); + bytes_transferred += bytes_sent; + if (bytes_sent == 0) { /* no more blocks */ break; } } @@ -226,9 +227,11 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque) /* try transferring iterative blocks of memory */ if (stage == 3) { + int bytes_sent; + /* flush all remaining blocks regardless of rate limiting */ - while (ram_save_block(f) != 0) { - bytes_transferred += TARGET_PAGE_SIZE; + while ((bytes_sent = ram_save_block(f)) != 0) { + bytes_transferred += bytes_sent; } cpu_physical_memory_set_dirty_tracking(0); }