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Re: [Qemu-devel] [RFC v2 26/33] migration: final handshake for the resum
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [RFC v2 26/33] migration: final handshake for the resume |
Date: |
Fri, 22 Sep 2017 12:56:12 +0100 |
User-agent: |
Mutt/1.8.3 (2017-05-23) |
* Peter Xu (address@hidden) wrote:
> Finish the last step to do the final handshake for the recovery.
>
> First source sends one MIG_CMD_RESUME to dst, telling that source is
> ready to resume.
>
> Then, dest replies with MIG_RP_MSG_RESUME_ACK to source, telling that
> dest is ready to resume (after switch to postcopy-active state).
>
> When source received the RESUME_ACK, it switches its state to
> postcopy-active, and finally the recovery is completed.
>
> Signed-off-by: Peter Xu <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> ---
> migration/migration.c | 28 ++++++++++++++++++++++++----
> 1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/migration/migration.c b/migration/migration.c
> index 19aed72..c9b7085 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1694,7 +1694,8 @@ static int migrate_handle_rp_resume_ack(MigrationState
> *s, uint32_t value)
> migrate_set_state(&s->state, MIGRATION_STATUS_POSTCOPY_RECOVER,
> MIGRATION_STATUS_POSTCOPY_ACTIVE);
>
> - /* TODO: notify send thread that time to continue send pages */
> + /* Notify send thread that time to continue send pages */
> + qemu_sem_post(&s->rp_state.rp_sem);
>
> return 0;
> }
> @@ -2169,6 +2170,21 @@ typedef enum MigThrError {
> MIG_THR_ERR_FATAL = 2,
> } MigThrError;
>
> +static int postcopy_resume_handshake(MigrationState *s)
> +{
> + qemu_savevm_send_postcopy_resume(s->to_dst_file);
> +
> + while (s->state == MIGRATION_STATUS_POSTCOPY_RECOVER) {
> + qemu_sem_wait(&s->rp_state.rp_sem);
> + }
> +
> + if (s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE) {
> + return 0;
> + }
> +
> + return -1;
> +}
> +
> /* Return zero if success, or <0 for error */
> static int postcopy_do_resume(MigrationState *s)
> {
> @@ -2186,10 +2202,14 @@ static int postcopy_do_resume(MigrationState *s)
> }
>
> /*
> - * TODO: handshake with dest using MIG_CMD_RESUME,
> - * MIG_RP_MSG_RESUME_ACK, then switch source state to
> - * "postcopy-active"
> + * Last handshake with destination on the resume (destination will
> + * switch to postcopy-active afterwards)
> */
> + ret = postcopy_resume_handshake(s);
> + if (ret) {
> + error_report("%s: handshake failed: %d", __func__, ret);
> + return ret;
> + }
>
> return 0;
> }
> --
> 2.7.4
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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