RE: [PATCH v9 11/13] x86/resctrl: Add sysfs interface to write mbm_local_bytes_config

[Moger, Babu]

[AMD Official Use Only - General]

Hi Reinette,

> -----Original Message-----
> From: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Sent: Thursday, December 15, 2022 12:26 PM
> To: Moger, Babu <Babu.Moger@xxxxxxx>; corbet@xxxxxxx;
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> Subject: Re: [PATCH v9 11/13] x86/resctrl: Add sysfs interface to write
> mbm_local_bytes_config
> 
> Hi Babu,
> 
> On 12/1/2022 7:37 AM, Babu Moger wrote:
> > The current event configuration for mbm_local_bytes can be changed by
> > the user by writing to the configuration file
> > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config.
> >
> 
> Same comments about subject line and usage of "current".

Sure,
> 
> > The event configuration settings are domain specific and will affect
> > all the CPUs in the domain.
> >
> > Following are the types of events supported:
> > ====
> ===========================================================
> > Bits   Description
> > ====
> ===========================================================
> > 6      Dirty Victims from the QOS domain to all types of memory
> > 5      Reads to slow memory in the non-local NUMA domain
> > 4      Reads to slow memory in the local NUMA domain
> > 3      Non-temporal writes to non-local NUMA domain
> > 2      Non-temporal writes to local NUMA domain
> > 1      Reads to memory in the non-local NUMA domain
> > 0      Reads to memory in the local NUMA domain
> > ====
> ===========================================================
> >
> > For example:
> > To change the mbm_local_bytes_config to count all the non-temporal
> > writes on domain 0, the bits 2 and 3 needs to be set which is 1100b (in hex
> 0xc).
> > Run the command.
> >     $echo  0=0xc > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
> >
> > To change the mbm_local_bytes to count only reads to local NUMA domain
> > 1, the bit 0 needs to be set which 1b (in hex 0x1). Run the command.
> >     $echo  1=0x1 > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
> >
> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> > ---
> >  arch/x86/kernel/cpu/resctrl/rdtgroup.c |   29
> ++++++++++++++++++++++++++++-
> >  1 file changed, 28 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > index 8a22a652a6e8..6897c480ae55 100644
> > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> > @@ -1641,6 +1641,32 @@ static ssize_t
> mbm_total_bytes_config_write(struct kernfs_open_file *of,
> >  	return ret ?: nbytes;
> >  }
> >
> > +static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
> > +					    char *buf, size_t nbytes,
> > +					    loff_t off)
> > +{
> > +	struct rdt_resource *r = of->kn->parent->priv;
> > +	int ret;
> > +
> > +	/* Valid input requires a trailing newline */
> > +	if (nbytes == 0 || buf[nbytes - 1] != '\n')
> > +		return -EINVAL;
> > +
> > +	cpus_read_lock();
> > +	mutex_lock(&rdtgroup_mutex);
> > +
> > +	rdt_last_cmd_clear();
> > +
> > +	buf[nbytes - 1] = '\0';
> > +
> > +	ret = mon_config_write(r, buf, QOS_L3_MBM_LOCAL_EVENT_ID);
> > +
> > +	mutex_unlock(&rdtgroup_mutex);
> > +	cpus_read_unlock();
> > +
> > +	return ret ?: nbytes;
> > +}
> > +
> >  /* rdtgroup information files for one cache resource. */  static
> > struct rftype res_common_files[] = {
> >  	{
> > @@ -1748,9 +1774,10 @@ static struct rftype res_common_files[] = {
> >  	},
> >  	{
> >  		.name		= "mbm_local_bytes_config",
> > -		.mode		= 0444,
> > +		.mode		= 0644,
> >  		.kf_ops		= &rdtgroup_kf_single_ops,
> >  		.seq_show	= mbm_local_bytes_config_show,
> > +		.write		= mbm_local_bytes_config_write,
> >  	},
> >  	{
> >  		.name		= "cpus",
> >
> >
> 
> With the subject and changelog comments addressed:
> 
> Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>

Thanks
Babu
> 
> Reinette