Re: [PATCH 2/3] virsh migrate: Add --available-switchover-bandwidth option

[Jiri Denemark <jdenemar@xxxxxxxxxx>]

On Thu, Jan 23, 2025 at 11:04:03 +0100, Jiri Denemark wrote:
> Signed-off-by: Jiri Denemark <jdenemar@xxxxxxxxxx>
> ---
>  docs/manpages/virsh.rst | 12 ++++++++++++
>  tools/virsh-domain.c    | 13 +++++++++++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index e801037c04..bf0436621b 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -3407,6 +3407,7 @@ migrate
>        [--parallel [--parallel-connections connections]]
>        [--bandwidth bandwidth] [--tls-destination hostname]
>        [--disks-uri URI] [--copy-storage-synchronous-writes]
> +      [--available-switchover-bandwidth bandwidth]
>  
>  Migrate domain to another host.  Add *--live* for live migration; <--p2p>
>  for peer-2-peer migration; *--direct* for direct migration; or *--tunnelled*
> @@ -3663,6 +3664,17 @@ the context of the existing socket because it is different from the file
>  representation of the socket and the context is chosen by its creator (usually
>  by using *setsockcreatecon{,_raw}()* functions).
>  
> +Optional *--available-switchover-bandwidth* overrides the automatically
> +computed bandwidth (in MiB/s) available for the final phase of (pre-copy)
> +migration during which CPUs are stopped and all the remaining memory and device
> +state is transferred. Knowing this bandwidth is important for accurate
> +estimation of the domain downtime and deciding the right moment for switching
> +over. Normally this would be estimated based on the bandwidth used by
> +migration, but this could be lower than the actual available bandwidth. Using
> +this option may help with migration convergence when the migration would keep
> +iterating over and over thinking there's not enough bandwidth to comply with
> +the configured maximum downtime.
> +
>  
>  migrate-compcache
>  -----------------
> diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> index 546db955a9..1280ace36b 100644
> --- a/tools/virsh-domain.c
> +++ b/tools/virsh-domain.c
> @@ -10788,6 +10788,10 @@ static const vshCmdOptDef opts_migrate[] = {
>       .type = VSH_OT_INT,
>       .help = N_("compress level for zstd compression")
>      },
> +    {.name = "available-switchover-bandwidth",
> +     .type = VSH_OT_INT,
> +     .help = N_("bandwidth (in MiB/s) available for the final phase of migration")
> +    },
>      {.name = NULL}
>  };
>  
> @@ -11114,6 +11118,15 @@ doMigrate(void *opaque)
>          }
>      }
>  
> +    if ((rv = vshCommandOptULongLong(ctl, cmd, "available-switchover-bandwidth", &ullOpt)) < 0) {
> +        goto out;
> +    } else if (rv > 0) {
> +        if (virTypedParamsAddULLong(&params, &nparams, &maxparams,
> +                                    VIR_MIGRATE_PARAM_BANDWIDTH_AVAIL_SWITCHOVER,
> +                                    ullOpt) < 0)
> +            goto save_error;
> +    }
> +

Oops, this hunk is misplaced. I managed to send this patch without a fix
squashed in.

Jirka