[PATCH 4/4] virsh: Add migrate options to set parallel compress level

[Jiri Denemark]

On Fri, Jan 20, 2023 at 16:47:43 +0800, Jiang Jiacheng wrote:
> Add migrate options: --compression-zlib-level
>                      --compression-zstd-level
> These options are used to set compress level for "zlib"
> or "zstd" during parallel migration if the compress method
> is specified.
> 
> Signed-off-by: Jiang Jiacheng <jiangjiacheng at huawei.com>
> ---
>  docs/manpages/virsh.rst | 22 +++++++++++++++-------
>  tools/virsh-domain.c    | 26 ++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+), 7 deletions(-)

I'll have similar comments to what I said for the public API.

> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index d5b614dc03..a837e3c1af 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -3359,7 +3359,8 @@ migrate
>        [--comp-xbzrle-cache] [--auto-converge] [auto-converge-initial]
>        [auto-converge-increment] [--persistent-xml file] [--tls]
>        [--postcopy-bandwidth bandwidth]
> -      [--parallel [--parallel-connections connections]]
> +      [--parallel [--parallel-connections connections]
> +      [--comp-zlib-level][--comp-zstd-level]]

These should be moved two lines above after [--comp-xbzrle-cache]. And
don't forget to add a space after ']'.

>        [--bandwidth bandwidth] [--tls-destination hostname]
>        [--disks-uri URI] [--copy-storage-synchronous-writes]
>  
> @@ -3466,11 +3467,14 @@ option for this to work.
>  with *--comp-methods*. Supported methods are "mt" and "xbzrle" and
>  can be used in any combination. When no methods are specified, a hypervisor
>  default methods will be used. QEMU defaults to "xbzrle". Compression methods
> -can be tuned further. *--comp-mt-level* sets compression level.
> -Values are in range from 0 to 9, where 1 is maximum speed and 9 is maximum
> -compression. *--comp-mt-threads* and *--comp-mt-dthreads* set the number
> -of compress threads on source and the number of decompress threads on target
> -respectively. *--comp-xbzrle-cache* sets size of page cache in bytes.
> +can be tuned further. When used with --parallel, supported methods are "zlib"
> +and "zstd" and if no methods are specified, QEMU will deaults to "none".
> +Note that compression method is defferent from compress migration and multifd
> +migration. *--comp-mt-level* sets compression level. Values are in range from
> +0 to 9, where 1 is maximum speed and 9 is maximum compression.
> +*--comp-mt-threads* and *--comp-mt-dthreads* set the number of compress threads
> +on source and the number of decompress threads on target respectively.
> +*--comp-xbzrle-cache* sets size of page cache in bytes.

The options for zlib and zstd compressions should be described here. I
can imagine something along the following lines:

    with *--comp-methods*. Supported methods are "mt", "xbzrle", "zlib",
    and "zstd". The supported set of methods and their combinations
    depend on a hypervisor and migration options. QEMU only supports
    "zlib" and "zstd" methods when *--parallel* is used and they cannot
    be used at once. When no methods are specified, a hypervisor default
    methods will be used. QEMU defaults to no compression for
    *--parallel* migration and "xbzrle" otherwise. Compression methods
    can be tuned further. *--comp-mt-level* sets compression level for
    "mt" method. Values are in range from 0 to 9, where 1 is maximum
    speed and 9 is maximum compression. *--comp-mt-threads* and
    *--comp-mt-dthreads* set the number of compress threads on source
    and the number of decompress threads on target respectively.
    *--comp-xbzrle-cache* sets size of page cache in bytes.
    *--comp-zlib-level* sets the compression level when using "zlib"
    method. Values are in range from 0 to 9 and defaults to 1.
    *--comp-zstd-level* sets the compression level when using "zstd"
    method. Values are in range from 0 to 20 and defaults to 1.

Although the semantics of the values need to be described as well. And
the same info needs to go to the first patch.

>  Providing *--tls* causes the migration to use the host configured TLS setup
>  (see migrate_tls_x509_cert_dir in /etc/libvirt/qemu.conf) in order to perform
> @@ -3486,7 +3490,11 @@ starting the migration.
>  parallel connections. The number of such connections can be set using
>  *--parallel-connections*. Parallel connections may help with saturating the
>  network link between the source and the target and thus speeding up the
> -migration.
> +migration. *--comp-zlib-level* sets the compression level when using "zlib"
> +as multifd migration's compression mesthod. Values are in range from 0 to 9
> +and defaults to 1. *--comp-zstd-level* sets the compression level when
> +using "zstd" as multifd migration's compression mesthod. Values are in range
> +from 0 to 20 and defaults to 1.
>  
>  Running migration can be canceled by interrupting virsh (usually using
>  ``Ctrl-C``) or by ``domjobabort`` command sent from another virsh instance.
> diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
> index 6b431bd1e5..bcf03e9567 100644
> --- a/tools/virsh-domain.c
> +++ b/tools/virsh-domain.c
> @@ -11095,6 +11095,14 @@ static const vshCmdOptDef opts_migrate[] = {
>       .type = VSH_OT_INT,
>       .help = N_("number of connections for parallel migration")
>      },
> +    {.name = "comp-zlib-level",
> +     .type = VSH_OT_INT,
> +     .help = N_("zlib compression level used in parallel migration")
> +    },
> +    {.name = "comp-zstd-level",
> +     .type = VSH_OT_INT,
> +     .help = N_("zstd compression level used in parallel migration")
> +    },

Virsh options should always be added at the end, i.e., just before

       {.name = NULL}


>      {.name = "bandwidth",
>       .type = VSH_OT_INT,
>       .help = N_("migration bandwidth limit in MiB/s")
...

Jirka