[PATCH v2] qom.json: default the prealloc-threads to smp-cpus

[PATCH v2] qom.json: default the prealloc-threads to smp-cpus

[Zhenyu Zhang]

Since the amount of prealloc-threads to smp-cpus is
defaulted in hostmem, so sync this information.

Signed-off-by: Zhenyu Zhang <zhenyzha@redhat.com>

v1: https://www.mail-archive.com/qemu-devel@nongnu.org/msg919682.html

Changelog
=========
v2:
  * This property is available since 5.0.                     (Philippe)
---
 qapi/qom.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qapi/qom.json b/qapi/qom.json
index 87fcad2423..b2f6bceec7 100644
--- a/qapi/qom.json
+++ b/qapi/qom.json
@@ -576,7 +576,7 @@
 #
 # @prealloc: if true, preallocate memory (default: false)
 #
-# @prealloc-threads: number of CPU threads to use for prealloc (default: 1)
+# @prealloc-threads: number of CPU threads to use for prealloc (default: smp-cpus) (since 5.0)
 #
 # @prealloc-context: thread context to use for creation of preallocation threads
 #                    (default: none) (since 7.2)
-- 
2.31.1

Re: [PATCH v2] qom.json: default the prealloc-threads to smp-cpus

[Markus Armbruster]

The subject is misleading, I'm afraid.  It suggests you're changing the
default.  You don't, you just fix its documentation.

Zhenyu Zhang <zhenyzha@redhat.com> writes:

> Since the amount of prealloc-threads to smp-cpus is
> defaulted in hostmem, so sync this information.

Covering history could be helpful.

Here's my try

    qapi/qom: Memory backend property prealloc-threads doc fix

    Commit ffac16fab3 "hostmem: introduce "prealloc-threads" property"
    (v5.0.0) changed the default number of threads from number of CPUs
    to 1.  This was deemed a regression, and fixed in commit f8d426a685
    "hostmem: default the amount of prealloc-threads to smp-cpus".
    Except the documentation remained unchanged.  Update it now.

>
> Signed-off-by: Zhenyu Zhang <zhenyzha@redhat.com>

The following part ...

> v1: https://www.mail-archive.com/qemu-devel@nongnu.org/msg919682.html
>
> Changelog
> =========
> v2:
>   * This property is available since 5.0.                     (Philippe)
> ---

... needs to go below the --- line, so it doesn't go into git.

>  qapi/qom.json | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/qapi/qom.json b/qapi/qom.json
> index 87fcad2423..b2f6bceec7 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -576,7 +576,7 @@
>  #
>  # @prealloc: if true, preallocate memory (default: false)
>  #
> -# @prealloc-threads: number of CPU threads to use for prealloc (default: 1)
> +# @prealloc-threads: number of CPU threads to use for prealloc (default: smp-cpus) (since 5.0)

Long line.

"smp-cpus" is not defined.  It's QOM property /machine/smp member @cpus,
commonly set with -M smp.cpus=N (or its sugared form -smp cpus=N).

Suggest

   # @prealloc-threads: number of CPU threads to use for prealloc
   # (default: number of CPUs) (since 5.0)

>  #
>  # @prealloc-context: thread context to use for creation of preallocation threads
>  #                    (default: none) (since 7.2)

Re: [PATCH v2] qom.json: default the prealloc-threads to smp-cpus

[Zhenyu Zhang]

Many thanks for your patient review, I learned a lot.
I will send v3 to correct it.

On Wed, Nov 9, 2022 at 5:52 PM Markus Armbruster <armbru@redhat.com> wrote:
>
> The subject is misleading, I'm afraid.  It suggests you're changing the
> default.  You don't, you just fix its documentation.
>
> Zhenyu Zhang <zhenyzha@redhat.com> writes:
>
> > Since the amount of prealloc-threads to smp-cpus is
> > defaulted in hostmem, so sync this information.
>
> Covering history could be helpful.
>
> Here's my try
>
>     qapi/qom: Memory backend property prealloc-threads doc fix
>
>     Commit ffac16fab3 "hostmem: introduce "prealloc-threads" property"
>     (v5.0.0) changed the default number of threads from number of CPUs
>     to 1.  This was deemed a regression, and fixed in commit f8d426a685
>     "hostmem: default the amount of prealloc-threads to smp-cpus".
>     Except the documentation remained unchanged.  Update it now.
>
> >
> > Signed-off-by: Zhenyu Zhang <zhenyzha@redhat.com>
>
> The following part ...
>
> > v1: https://www.mail-archive.com/qemu-devel@nongnu.org/msg919682.html
> >
> > Changelog
> > =========
> > v2:
> >   * This property is available since 5.0.                     (Philippe)
> > ---
>
> ... needs to go below the --- line, so it doesn't go into git.
>
> >  qapi/qom.json | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/qapi/qom.json b/qapi/qom.json
> > index 87fcad2423..b2f6bceec7 100644
> > --- a/qapi/qom.json
> > +++ b/qapi/qom.json
> > @@ -576,7 +576,7 @@
> >  #
> >  # @prealloc: if true, preallocate memory (default: false)
> >  #
> > -# @prealloc-threads: number of CPU threads to use for prealloc (default: 1)
> > +# @prealloc-threads: number of CPU threads to use for prealloc (default: smp-cpus) (since 5.0)
>
> Long line.
>
> "smp-cpus" is not defined.  It's QOM property /machine/smp member @cpus,
> commonly set with -M smp.cpus=N (or its sugared form -smp cpus=N).
>
> Suggest
>
>    # @prealloc-threads: number of CPU threads to use for prealloc
>    # (default: number of CPUs) (since 5.0)
>
> >  #
> >  # @prealloc-context: thread context to use for creation of preallocation threads
> >  #                    (default: none) (since 7.2)
>