linux-kernel - Re: [PATCH v1 05/31] x86/resctrl: Remove rdtgroup from update_cpu_closid

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Date: Tue, 16 Apr 2024 17:17:06 +0100
From: Dave Martin <Dave.Martin@....com>
To: "Moger, Babu" <babu.moger@....com>
Cc: James Morse <james.morse@....com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Fenghua Yu <fenghua.yu@...el.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	H Peter Anvin <hpa@...or.com>, shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com, lcherian@...vell.com,
	bobo.shaobowang@...wei.com, tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com, Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>, peternewman@...gle.com,
	dfustini@...libre.com, amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Rex Nie <rex.nie@...uarmicro.com>
Subject: Re: [PATCH v1 05/31] x86/resctrl: Remove rdtgroup from
 update_cpu_closid_rmid()

On Mon, Apr 15, 2024 at 03:40:46PM -0500, Moger, Babu wrote:
> Hi James/Dave,
> 
> On 3/21/24 11:50, James Morse wrote:
> > update_cpu_closid_rmid() takes a struct rdtgroup as an argument, which
> > it uses to update the local CPUs default pqr values. This is a problem
> > once the resctrl parts move out to /fs/, as the arch code cannot
> > poke around inside struct rdtgroup.
> > 
> > Rename update_cpu_closid_rmid() as resctrl_arch_sync_cpus_defaults()
> > to be used as the target of an IPI, and pass the effective CLOSID
> > and RMID in a new struct.
> > 
> > Signed-off-by: James Morse <james.morse@....com>
> > ---
> >  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 19 +++++++++++++++----
> >  include/linux/resctrl.h                | 11 +++++++++++
> >  2 files changed, 26 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > index 5d2c1ce5b6b1..18f097fce51e 100644
> > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > @@ -341,13 +341,13 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
> >   * from update_closid_rmid() is protected against __switch_to() because
> >   * preemption is disabled.
> >   */
> > -static void update_cpu_closid_rmid(void *info)
> > +void resctrl_arch_sync_cpu_defaults(void *info)
> 
> How about keeping the name similar to the old name?
> 
> resctrl_arch_update_cpu_defaults

Ack (Reinette made a similar comment.)

> 
> >  {
> > -	struct rdtgroup *r = info;
> > +	struct resctrl_cpu_sync *r = info;
> >  
> >  	if (r) {
> >  		this_cpu_write(pqr_state.default_closid, r->closid);
> > -		this_cpu_write(pqr_state.default_rmid, r->mon.rmid);
> > +		this_cpu_write(pqr_state.default_rmid, r->rmid);
> >  	}
> >  
> >  	/*

[...]

> > diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> > index 6e87bc95f5ea..2b79e4159507 100644
> > --- a/include/linux/resctrl.h
> > +++ b/include/linux/resctrl.h
> > @@ -220,6 +220,17 @@ struct resctrl_schema {
> >  	u32				num_closid;
> >  };
> >  
> > +struct resctrl_cpu_sync {
> 
> How about changing it to  resctrl_cpu_defaults?
> 
> > +	u32 closid;
> > +	u32 rmid;
> > +};

[...]

> -- 
> Thanks
> Babu Moger
> 

Yes, your name describes what the struct means, so renaming it as per
your suggestion does make sense.

I'll make a note.

Cheers
---Dave