[PATCH 2/3] virsh: Add migrate options to set parallel compress level

[Jiri Denemark]

On Fri, Feb 24, 2023 at 17:27:11 +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 | 29 ++++++++++++++++++++---------
>  tools/virsh-domain.c    | 26 ++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+), 9 deletions(-)
> 
> diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
> index d5b614dc03..ccad02bd94 100644
> --- a/docs/manpages/virsh.rst
> +++ b/docs/manpages/virsh.rst
> @@ -3356,7 +3356,8 @@ migrate
>        [--xml file] [--migrate-disks disk-list] [--disks-port port]
>        [--compressed] [--comp-methods method-list]
>        [--comp-mt-level] [--comp-mt-threads] [--comp-mt-dthreads]
> -      [--comp-xbzrle-cache] [--auto-converge] [auto-converge-initial]
> +      [--comp-xbzrle-cache] [--comp-zlib-level] [--comp-zstd-level]
> +      [--auto-converge] [auto-converge-initial]
>        [auto-converge-increment] [--persistent-xml file] [--tls]
>        [--postcopy-bandwidth bandwidth]
>        [--parallel [--parallel-connections connections]]
> @@ -3463,14 +3464,24 @@ to post-copy upon timeout; migration has to be started with *--postcopy*
>  option for this to work.
>  
>  *--compressed* activates compression, the compression method is chosen
> -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.
> +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.

This would suggest --parallel --compressed is allowed and results in no
compression as that is the default for QEMU. I think it would be better
to explicitly say that using --compressed without --comp-method is not
allowed with --parallel.

> +*--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, where 0 is no compression,
> +1 is maximum speed and 9 is maximum compression.
> +*--comp-zstd-level* sets the compression level when using "zstd" method.
> +Values are in range from 0 to 20 and defaults to 1, where 0 is no compression,
> +1 is maximum speed and 20 is maximum compression.
>  
>  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
...

With the following suggested changes
Reviewed-by: Jiri Denemark <jdenemar at redhat.com>

diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
index 738d3b7fb9..f4e5a0bd62 100644
--- a/docs/manpages/virsh.rst
+++ b/docs/manpages/virsh.rst
@@ -3485,19 +3485,20 @@ 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, where 0 is no compression,
-1 is maximum speed and 9 is maximum compression.
-*--comp-zstd-level* sets the compression level when using "zstd" method.
-Values are in range from 0 to 20 and defaults to 1, where 0 is no compression,
-1 is maximum speed and 20 is maximum compression.
+be used. QEMU defaults to "xbzrle" as long as *--parallel* is not used.
+For *--parallel* migrations QEMU does not provide any default compression
+method and thus it has to be specified explicitly using *--comp-method*.
+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, where 0 is no compression, 1 is maximum speed and 9 is maximum
+compression. *--comp-zstd-level* sets the compression level when using "zstd"
+method. Values are in range from 0 to 20 and defaults to 1, where 0 is no
+compression, 1 is maximum speed and 20 is maximum compression.

 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