On Wed, Feb 15, 2023 at 07:02:31PM +0100, Juan Quintela wrote:
> We need to add a new flag to mean to flush at that point.
> Notice that we still flush at the end of setup and at the end of
> complete stages.
>
> Signed-off-by: Juan Quintela <quint...@redhat.com>
Acked-by: Peter Xu <pet...@redhat.com>
One nitpick below.
>
> ---
>
> Add missing qemu_fflush(), now it passes all tests always.
> ---
> qapi/migration.json | 3 ---
> migration/migration.c | 6 +-----
> migration/ram.c | 28 +++++++++++++++++++++++++++-
> 3 files changed, 28 insertions(+), 9 deletions(-)
>
> diff --git a/qapi/migration.json b/qapi/migration.json
> index 3afd81174d..34e1657c4e 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -491,9 +491,6 @@
> # suboptimal (we flush too many
> # times).
> # Default value is false.
> -# Setting this capability has no
> -# effect until the patch that
> -# removes this comment.
> # (since 8.0)
> #
> # Features:
> diff --git a/migration/migration.c b/migration/migration.c
> index cfba0da005..74bcc16848 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2706,11 +2706,7 @@ bool migrate_multifd_flush_after_each_section(void)
> {
> MigrationState *s = migrate_get_current();
>
> - /*
> - * Until the patch that remove this comment, we always return that
> - * the capability is enabled.
> - */
> - return true ||
> s->enabled_capabilities[MIGRATION_CAPABILITY_MULTIFD_FLUSH_AFTER_EACH_SECTION];
> + return
> s->enabled_capabilities[MIGRATION_CAPABILITY_MULTIFD_FLUSH_AFTER_EACH_SECTION];
> }
>
> bool migrate_pause_before_switchover(void)
> diff --git a/migration/ram.c b/migration/ram.c
> index 6191dac9af..bc5eb1640b 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -85,6 +85,7 @@
> #define RAM_SAVE_FLAG_XBZRLE 0x40
> /* 0x80 is reserved in qemu-file.h for RAM_SAVE_FLAG_HOOK */
> #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
> +#define RAM_SAVE_FLAG_MULTIFD_FLUSH 0x200
> /* We can't use any flag that is bigger than 0x200 */
>
> int (*xbzrle_encode_buffer_func)(uint8_t *, uint8_t *, int,
> @@ -1595,6 +1596,7 @@ retry:
> * associated with the search process.
> *
> * Returns:
> + * <0: An error happened
> * PAGE_ALL_CLEAN: no dirty page found, give up
> * PAGE_TRY_AGAIN: no dirty page found, retry for next block
> * PAGE_DIRTY_FOUND: dirty page found
> @@ -1622,6 +1624,15 @@ static int find_dirty_block(RAMState *rs,
> PageSearchStatus *pss)
> pss->page = 0;
> pss->block = QLIST_NEXT_RCU(pss->block, next);
> if (!pss->block) {
> + if (!migrate_multifd_flush_after_each_section()) {
> + QEMUFile *f = rs->pss[RAM_CHANNEL_PRECOPY].pss_channel;
> + int ret = multifd_send_sync_main(f);
> + if (ret < 0) {
> + return ret;
> + }
> + qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> + qemu_fflush(f);
> + }
> /*
> * If memory migration starts over, we will meet a dirtied page
> * which may still exists in compression threads's ring, so we
> @@ -2614,6 +2625,9 @@ static int ram_find_and_save_block(RAMState *rs)
> break;
> } else if (res == PAGE_TRY_AGAIN) {
> continue;
> + } else if (res < 0) {
> + pages = res;
> + break;
> }
> }
> }
> @@ -3300,6 +3314,10 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
> return ret;
> }
>
> + if (!migrate_multifd_flush_after_each_section()) {
> + qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> + }
> +
> qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> qemu_fflush(f);
>
> @@ -3485,6 +3503,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
> return ret;
> }
>
> + if (!migrate_multifd_flush_after_each_section()) {
> + qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> + }
> qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> qemu_fflush(f);
>
> @@ -4169,7 +4190,9 @@ int ram_load_postcopy(QEMUFile *f, int channel)
> }
> decompress_data_with_multi_threads(f, page_buffer, len);
> break;
> -
> + case RAM_SAVE_FLAG_MULTIFD_FLUSH:
> + multifd_recv_sync_main();
> + break;
> case RAM_SAVE_FLAG_EOS:
> /* normal exit */
> if (migrate_multifd_flush_after_each_section()) {
We could have dropped RAM_SAVE_FLAG_MULTIFD_FLUSH and RAM_SAVE_FLAG_EOS for
now until we support postcopy+multifd.
Here it's not only about enabling them together, but it's about running
them in parallel, which I doubt whether it can really be implemented at all
due to the fundamentally concepts difference between multifd & postcopy.. :(
> @@ -4443,6 +4466,9 @@ static int ram_load_precopy(QEMUFile *f)
> break;
> }
> break;
> + case RAM_SAVE_FLAG_MULTIFD_FLUSH:
> + multifd_recv_sync_main();
> + break;
> case RAM_SAVE_FLAG_EOS:
> /* normal exit */
> if (migrate_multifd_flush_after_each_section()) {
> --
> 2.39.1
>
>
--
Peter Xu
