docs/about/deprecated.rst | 16 ---------------- docs/about/removed-features.rst | 15 +++++++++++++++ hw/core/machine-smp.c | 5 +++-- 3 files changed, 18 insertions(+), 18 deletions(-)
From: Zhao Liu <zhao1.liu@intel.com>
The "parameter=0" SMP configurations have been marked as deprecated
since v6.2.
For these cases, -smp currently returns the warning and adjusts the
zeroed parameters to 1 by default.
Remove the above compatibility logic in v9.0, and return error directly
if any -smp parameter is set as 0.
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
docs/about/deprecated.rst | 16 ----------------
docs/about/removed-features.rst | 15 +++++++++++++++
hw/core/machine-smp.c | 5 +++--
3 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index 36bd3e15ef06..872974640252 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -36,22 +36,6 @@ and will cause a warning.
The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on``
rather than ``delay=off``.
-``-smp`` ("parameter=0" SMP configurations) (since 6.2)
-'''''''''''''''''''''''''''''''''''''''''''''''''''''''
-
-Specified CPU topology parameters must be greater than zero.
-
-In the SMP configuration, users should either provide a CPU topology
-parameter with a reasonable value (greater than zero) or just omit it
-and QEMU will compute the missing value.
-
-However, historically it was implicitly allowed for users to provide
-a parameter with zero value, which is meaningless and could also possibly
-cause unexpected results in the -smp parsing. So support for this kind of
-configurations (e.g. -smp 8,sockets=0) is deprecated since 6.2 and will
-be removed in the near future, users have to ensure that all the topology
-members described with -smp are greater than zero.
-
Plugin argument passing through ``arg=<string>`` (since 6.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst
index 417a0e4fa1d9..f9cf874f7b1f 100644
--- a/docs/about/removed-features.rst
+++ b/docs/about/removed-features.rst
@@ -489,6 +489,21 @@ The ``-singlestep`` option has been turned into an accelerator property,
and given a name that better reflects what it actually does.
Use ``-accel tcg,one-insn-per-tb=on`` instead.
+``-smp`` ("parameter=0" SMP configurations) (removed in 9.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Specified CPU topology parameters must be greater than zero.
+
+In the SMP configuration, users should either provide a CPU topology
+parameter with a reasonable value (greater than zero) or just omit it
+and QEMU will compute the missing value.
+
+However, historically it was implicitly allowed for users to provide
+a parameter with zero value, which is meaningless and could also possibly
+cause unexpected results in the -smp parsing. So support for this kind of
+configurations (e.g. -smp 8,sockets=0) is removed since 9.0, users have
+to ensure that all the topology members described with -smp are greater
+than zero.
User-mode emulator command line arguments
-----------------------------------------
diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c
index 25019c91ee36..96533886b14e 100644
--- a/hw/core/machine-smp.c
+++ b/hw/core/machine-smp.c
@@ -105,8 +105,9 @@ void machine_parse_smp_config(MachineState *ms,
(config->has_cores && config->cores == 0) ||
(config->has_threads && config->threads == 0) ||
(config->has_maxcpus && config->maxcpus == 0)) {
- warn_report("Deprecated CPU topology (considered invalid): "
- "CPU topology parameters must be greater than zero");
+ error_setg(errp, "Invalid CPU topology: "
+ "CPU topology parameters must be greater than zero");
+ return;
}
/*
--
2.34.1On Mon, 4 Mar 2024 at 10:02, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
> diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c
> index 25019c91ee36..96533886b14e 100644
> --- a/hw/core/machine-smp.c
> +++ b/hw/core/machine-smp.c
> @@ -105,8 +105,9 @@ void machine_parse_smp_config(MachineState *ms,
> (config->has_cores && config->cores == 0) ||
> (config->has_threads && config->threads == 0) ||
> (config->has_maxcpus && config->maxcpus == 0)) {
> - warn_report("Deprecated CPU topology (considered invalid): "
> - "CPU topology parameters must be greater than zero");
> + error_setg(errp, "Invalid CPU topology: "
> + "CPU topology parameters must be greater than zero");
> + return;
> }
unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
...
if (config->has_maxcpus && config->maxcpus == 0)
* The check (has_maxcpus && maxcpus == 0) seems to be repeating above,
maybe we could check if (maxcpus == 0) error_setg(). And same for
other topology parameters?
* Also a check to ensure cpus <= maxcpus is required I think.
Thank you.
---
- Prasad
Hi Prasad,
On Mon, Mar 04, 2024 at 11:23:58AM +0530, Prasad Pandit wrote:
> Date: Mon, 4 Mar 2024 11:23:58 +0530
> From: Prasad Pandit <ppandit@redhat.com>
> Subject: Re: [PATCH] hw/core/machine-smp: Remove deprecated "parameter=0"
> SMP configurations
>
> On Mon, 4 Mar 2024 at 10:02, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
> > diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c
> > index 25019c91ee36..96533886b14e 100644
> > --- a/hw/core/machine-smp.c
> > +++ b/hw/core/machine-smp.c
> > @@ -105,8 +105,9 @@ void machine_parse_smp_config(MachineState *ms,
> > (config->has_cores && config->cores == 0) ||
> > (config->has_threads && config->threads == 0) ||
> > (config->has_maxcpus && config->maxcpus == 0)) {
> > - warn_report("Deprecated CPU topology (considered invalid): "
> > - "CPU topology parameters must be greater than zero");
> > + error_setg(errp, "Invalid CPU topology: "
> > + "CPU topology parameters must be greater than zero");
> > + return;
> > }
>
> unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
This indicates the default maxcpus is initialized as 0 if user doesn't
specifies it.
For this case - no user configuration - maxcpus will be re-calculated
as:
maxcpus = maxcpus > 0 ? maxcpus : drawers * books * sockets * dies *
clusters * cores * threads; (*)
> ...
> if (config->has_maxcpus && config->maxcpus == 0)
This check only wants to identify the case that user sets the 0.
>
> * The check (has_maxcpus && maxcpus == 0) seems to be repeating above,
> maybe we could check if (maxcpus == 0) error_setg().
If the default maxcpus is initialized as 0, then (maxcpus == 0) will
fail if user doesn't set maxcpus.
However, we could initialize maxcpus as other default value, e.g.,
maxcpus = config->has_maxcpus ? config->maxcpus : 1.
But it is still necessary to distinguish whether maxcpus is user-set or
auto-initialized.
If it is user-set, -smp should fail is there's invalid maxcpus/invalid
topology.
Otherwise, if it is auto-initialized, its value should be adjusted based
on other topology components as the above calculation in (*).
> And same for
> other topology parameters?
Other parameters also have the similar needs to distinguish if they're
set by user. So the check needs to also cover has_* fields.
> * Also a check to ensure cpus <= maxcpus is required I think.
>
Yes, the valid topology needs this. This code block already covers this
case ;-):
if (maxcpus < cpus) {
g_autofree char *topo_msg = cpu_hierarchy_to_string(ms);
error_setg(errp, "Invalid CPU topology: "
"maxcpus must be equal to or greater than smp: "
"%s == maxcpus (%u) < smp_cpus (%u)",
topo_msg, maxcpus, cpus);
return;
}
Thanks,
Zhao
Hello Zhao,
On Mon, 4 Mar 2024 at 12:19, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
> > unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
>
> This indicates the default maxcpus is initialized as 0 if user doesn't
> specifies it.
* 'has_maxcpus' should be set only if maxcpus > 0. If maxcpus == 0,
then setting 'has_maxcpus=1' seems convoluted.
> However, we could initialize maxcpus as other default value, e.g.,
>
> maxcpus = config->has_maxcpus ? config->maxcpus : 1.
===
hw/core/machine.c
machine_initfn
/* default to mc->default_cpus */
ms->smp.cpus = mc->default_cpus;
ms->smp.max_cpus = mc->default_cpus;
static void machine_class_base_init(ObjectClass *oc, void *data)
{
MachineClass *mc = MACHINE_CLASS(oc);
mc->max_cpus = mc->max_cpus ?: 1;
mc->min_cpus = mc->min_cpus ?: 1;
mc->default_cpus = mc->default_cpus ?: 1;
}
===
* Looking at the above bits, it seems smp.cpus & smp.max_cpus are
initialised to 1 via default_cpus in MachineClass object.
>> if (config->has_maxcpus && config->maxcpus == 0)
> This check only wants to identify the case that user sets the 0.
> If the default maxcpus is initialized as 0, then (maxcpus == 0) will
> fail if user doesn't set maxcpus.
>
> But it is still necessary to distinguish whether maxcpus is user-set or
> auto-initialized.
* If it is set to zero(0) either by user or by auto-initialise, it is
still invalid, right?
> If it is user-set, -smp should fail is there's invalid maxcpus/invalid
> topology.
>
> Otherwise, if it is auto-initialized, its value should be adjusted based
> on other topology components as the above calculation in (*).
* Why have such diverging ways?
* Could we simplify it as
- If cpus/maxcpus==0, it is invalid, show an error and exit.
- If cpus/maxcpus > 0, but incorrect for topology, then
re-calculate the correct value based on topology parameters. If the
re-calculated value is still incorrect or unsatisfactory, then show an
error and exit.
* Saying that user setting cpu/maxcpus=0 is invalid and
auto-initialising it to zero(0) is valid, is not consistent.
...wdyt?
---
- Prasad
Hi Prasad,
> On Mon, 4 Mar 2024 at 12:19, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
> > > unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
> >
> > This indicates the default maxcpus is initialized as 0 if user doesn't
> > specifies it.
>
> * 'has_maxcpus' should be set only if maxcpus > 0. If maxcpus == 0,
> then setting 'has_maxcpus=1' seems convoluted.
After simple test, if user sets maxcpus as 0, the has_maxcpus will be
true as well...I think it's related with QAPI code generation logic.
> > However, we could initialize maxcpus as other default value, e.g.,
> >
> > maxcpus = config->has_maxcpus ? config->maxcpus : 1.
> ===
> hw/core/machine.c
> machine_initfn
> /* default to mc->default_cpus */
> ms->smp.cpus = mc->default_cpus;
> ms->smp.max_cpus = mc->default_cpus;
>
> static void machine_class_base_init(ObjectClass *oc, void *data)
> {
> MachineClass *mc = MACHINE_CLASS(oc);
> mc->max_cpus = mc->max_cpus ?: 1;
> mc->min_cpus = mc->min_cpus ?: 1;
> mc->default_cpus = mc->default_cpus ?: 1;
> }
> ===
> * Looking at the above bits, it seems smp.cpus & smp.max_cpus are
> initialised to 1 via default_cpus in MachineClass object.
Yes.
The maxcpus I mentioned is a local virable in
machine_parse_smp_config(), whihc is used to do sanity-check check.
In machine_parse_smp_config(), when we can confirm the topology is
valid, then ms->smp.cpus and ms->smp.max_cpus are set with the valid
virables (cpus and maxcpus).
> >> if (config->has_maxcpus && config->maxcpus == 0)
> > This check only wants to identify the case that user sets the 0.
> > If the default maxcpus is initialized as 0, then (maxcpus == 0) will
> > fail if user doesn't set maxcpus.
> >
> > But it is still necessary to distinguish whether maxcpus is user-set or
> > auto-initialized.
>
> * If it is set to zero(0) either by user or by auto-initialise, it is
> still invalid, right?
The latter, "auto-initialise", means user could omit "cpus" and "maxcpus"
parameters in -smp.
Even though the local variable "cpus" and "maxcpus" are initialized as
0, eventually ms->smp.cpus and ms->smp.max_cpus will still have the
valid values.
> > If it is user-set, -smp should fail is there's invalid maxcpus/invalid
> > topology.
> >
> > Otherwise, if it is auto-initialized, its value should be adjusted based
> > on other topology components as the above calculation in (*).
>
> * Why have such diverging ways?
> * Could we simplify it as
> - If cpus/maxcpus==0, it is invalid, show an error and exit.
Hmm, the origial behavior means if user doesn't set cpus=*/maxcpus=* in
-smp, then QEMU will auto-complete these 2 fields.
If we also return error for the above case that user omits cpus and
maxcpus parameters, then this change the QEMU's API and we need to mark
feature that the cpus/maxcpus parameter can be omitted as deprecated and
remove it out. Just like what I did in this patch for zeroed-parameter
case.
I feel if there's no issue then it's not necessary to change the API. Do
you agree?
> - If cpus/maxcpus > 0, but incorrect for topology, then
> re-calculate the correct value based on topology parameters. If the
> re-calculated value is still incorrect or unsatisfactory, then show an
> error and exit.
Yes, this case is right.
> * Saying that user setting cpu/maxcpus=0 is invalid and
> auto-initialising it to zero(0) is valid, is not consistent.
>
I think "auto-initialising it to zero(0)" doesn't means we re-initialize
ms->smp.cpus and ms->smp.max_cpus as 0 (these 2 fields store actual basic
topology information and they're defult as 1 as you said above).
Does my explaination address your concern? ;-)
Thanks,
Zhao
Hi,
On Tue, 5 Mar 2024 at 12:59, Zhao Liu <zhao1.liu@linux.intel.com> wrote:
> After simple test, if user sets maxcpus as 0, the has_maxcpus will be
> true as well...I think it's related with QAPI code generation logic.
* Right.
[Maybe we digressed a bit in the discussion, so I snipped much of the
details here. Sorry about that.]
* "if user sets maxcpus as 0, the has_maxcpus will be true as well",
ie if 'has_*' fields are always set
unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0;
then checking 'config->has_maxcpus ?' above is probably not required I
think. It could just be
maxcpus = config->maxcpus
If a user does not specify config->maxcpus with -smp option, then it
could default to zero(0) in 'config' parameter? (same for other config
fields)
* If such change requires API changes (I'm not sure how), then
probably it is outside the scope of this patch.
...wdyt?
Thank you.
---
- Prasad
Hi Prasad, > On Tue, 5 Mar 2024 at 12:59, Zhao Liu <zhao1.liu@linux.intel.com> wrote: > > After simple test, if user sets maxcpus as 0, the has_maxcpus will be > > true as well...I think it's related with QAPI code generation logic. > > * Right. > > [Maybe we digressed a bit in the discussion, so I snipped much of the > details here. Sorry about that.] > > * "if user sets maxcpus as 0, the has_maxcpus will be true as well", > ie if 'has_*' fields are always set > > unsigned maxcpus = config->has_maxcpus ? config->maxcpus : 0; > > then checking 'config->has_maxcpus ?' above is probably not required I > think. It could just be > > maxcpus = config->maxcpus Yes. > If a user does not specify config->maxcpus with -smp option, then it > could default to zero(0) in 'config' parameter? (same for other config > fields) Yes. I could post another series for this cleanup soon. > * If such change requires API changes (I'm not sure how), then > probably it is outside the scope of this patch. > > ...wdyt? > The above change you suggested doesn't require API changes ;-). Thanks, Zhao
Hello Zhao, On Wed, 6 Mar 2024 at 08:49, Zhao Liu <zhao1.liu@linux.intel.com> wrote: >> then checking 'config->has_maxcpus ?' above is probably not required I >> think. It could just be >> >> maxcpus = config->maxcpus > > Yes. > > > If a user does not specify config->maxcpus with -smp option, then it > > could default to zero(0) in 'config' parameter? (same for other config > > fields) > > Yes. I could post another series for this cleanup soon. > The above change you suggested doesn't require API changes ;-). * Great! (Communication is the most difficult skill to master. :)) * If you plan to send a separate patch for above refactoring, then I'd add Reviewed-by for this one. Reviewed-by: Prasad Pandit <pjp@fedoraproject.org> Thank you. --- - Prasad
On Wed, Mar 06, 2024 at 10:19:41AM +0530, Prasad Pandit wrote: > Date: Wed, 6 Mar 2024 10:19:41 +0530 > From: Prasad Pandit <ppandit@redhat.com> > Subject: Re: [PATCH] hw/core/machine-smp: Remove deprecated "parameter=0" > SMP configurations > > Hello Zhao, > > On Wed, 6 Mar 2024 at 08:49, Zhao Liu <zhao1.liu@linux.intel.com> wrote: > >> then checking 'config->has_maxcpus ?' above is probably not required I > >> think. It could just be > >> > >> maxcpus = config->maxcpus > > > > Yes. > > > > > If a user does not specify config->maxcpus with -smp option, then it > > > could default to zero(0) in 'config' parameter? (same for other config > > > fields) > > > > Yes. I could post another series for this cleanup soon. > > The above change you suggested doesn't require API changes ;-). > > * Great! (Communication is the most difficult skill to master. :)) > > * If you plan to send a separate patch for above refactoring, then I'd > add Reviewed-by for this one. Yeah, I will send a series, which will also include this patch, to avoid trivial smp cleanup fragmentation. > Reviewed-by: Prasad Pandit <pjp@fedoraproject.org> Thanks! -Zhao
On 04/03/2024 05.45, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
>
> The "parameter=0" SMP configurations have been marked as deprecated
> since v6.2.
>
> For these cases, -smp currently returns the warning and adjusts the
> zeroed parameters to 1 by default.
>
> Remove the above compatibility logic in v9.0, and return error directly
> if any -smp parameter is set as 0.
>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> docs/about/deprecated.rst | 16 ----------------
> docs/about/removed-features.rst | 15 +++++++++++++++
> hw/core/machine-smp.c | 5 +++--
> 3 files changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
> index 36bd3e15ef06..872974640252 100644
> --- a/docs/about/deprecated.rst
> +++ b/docs/about/deprecated.rst
> @@ -36,22 +36,6 @@ and will cause a warning.
> The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on``
> rather than ``delay=off``.
>
> -``-smp`` ("parameter=0" SMP configurations) (since 6.2)
> -'''''''''''''''''''''''''''''''''''''''''''''''''''''''
> -
> -Specified CPU topology parameters must be greater than zero.
> -
> -In the SMP configuration, users should either provide a CPU topology
> -parameter with a reasonable value (greater than zero) or just omit it
> -and QEMU will compute the missing value.
> -
> -However, historically it was implicitly allowed for users to provide
> -a parameter with zero value, which is meaningless and could also possibly
> -cause unexpected results in the -smp parsing. So support for this kind of
> -configurations (e.g. -smp 8,sockets=0) is deprecated since 6.2 and will
> -be removed in the near future, users have to ensure that all the topology
> -members described with -smp are greater than zero.
> -
> Plugin argument passing through ``arg=<string>`` (since 6.1)
> ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
>
> diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst
> index 417a0e4fa1d9..f9cf874f7b1f 100644
> --- a/docs/about/removed-features.rst
> +++ b/docs/about/removed-features.rst
> @@ -489,6 +489,21 @@ The ``-singlestep`` option has been turned into an accelerator property,
> and given a name that better reflects what it actually does.
> Use ``-accel tcg,one-insn-per-tb=on`` instead.
>
> +``-smp`` ("parameter=0" SMP configurations) (removed in 9.0)
> +''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
> +
> +Specified CPU topology parameters must be greater than zero.
> +
> +In the SMP configuration, users should either provide a CPU topology
> +parameter with a reasonable value (greater than zero) or just omit it
> +and QEMU will compute the missing value.
> +
> +However, historically it was implicitly allowed for users to provide
> +a parameter with zero value, which is meaningless and could also possibly
> +cause unexpected results in the -smp parsing. So support for this kind of
> +configurations (e.g. -smp 8,sockets=0) is removed since 9.0, users have
> +to ensure that all the topology members described with -smp are greater
> +than zero.
>
> User-mode emulator command line arguments
> -----------------------------------------
> diff --git a/hw/core/machine-smp.c b/hw/core/machine-smp.c
> index 25019c91ee36..96533886b14e 100644
> --- a/hw/core/machine-smp.c
> +++ b/hw/core/machine-smp.c
> @@ -105,8 +105,9 @@ void machine_parse_smp_config(MachineState *ms,
> (config->has_cores && config->cores == 0) ||
> (config->has_threads && config->threads == 0) ||
> (config->has_maxcpus && config->maxcpus == 0)) {
> - warn_report("Deprecated CPU topology (considered invalid): "
> - "CPU topology parameters must be greater than zero");
> + error_setg(errp, "Invalid CPU topology: "
> + "CPU topology parameters must be greater than zero");
> + return;
> }
Reviewed-by: Thomas Huth <thuth@redhat.com>
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