Anyone interested by this diff?
On 12 mai 2010, at 15:12, Pierre Riteau wrote:
> 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 <pierre.rit...@irisa.fr>
> ---
> arch_init.c | 21 ++++++++++++---------
> 1 files changed, 12 insertions(+), 9 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index cf6b7b0..76317af 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);
> }
> --
> 1.7.1
>
>
--
Pierre Riteau -- PhD student, Myriads team, IRISA, Rennes, France
http://perso.univ-rennes1.fr/pierre.riteau/
