Re: [PATCH] fs/resctrl,x86/resctrl: Factor mba rounding to be per-arch

[Chen, Yu C]

On 10/11/2025 12:48 AM, Reinette Chatre wrote:
> Hi Dave,
>
> On 9/30/25 8:40 AM, Dave Martin wrote:
> > On Mon, Sep 29, 2025 at 09:09:35AM -0700, Reinette Chatre wrote:
> > > On 9/29/25 6:56 AM, Dave Martin wrote:
> > > > On Thu, Sep 25, 2025 at 03:58:35PM -0700, Luck, Tony wrote:
> > > > > On Mon, Sep 22, 2025 at 04:04:40PM +0100, Dave Martin wrote:

[snip]

> > Anyway, going back to the "#" convention:
> >
> > If the initial read of schemata has the new entries "pre-commented",
> > then userspace wouldn't need to know about the new entries.  It could
> > just tweak the MB entry (which it knows about), and write the file back:
> >
> > 	MB: 0=43
> > 	# MB_HW: 0=2
> > 	# MB_MIN: 0=1
> > 	# MB_MAX: 0=2
> >
> > then resctrl knows to ignore the hashed lines, and so reading the file
> > back gives:
> >
> > 	MB: 0=43
> > 	# MB_HW: 0=3
> > 	# MB_MIN: 0=2
> > 	# MB_MAX: 0=3


May I ask if introducing the pre-commented lines is intended to prevent
control conflicts over the same MBA? If this is the case, I wonder if,
instead of exposing both MB and the pre-commented MB_HW_X in one file,
it would be  feasible to introduce a new mount option (such as "hw") to
 make the legacy MB and MB_HW_X mutually exclusive. If the user specifies
 "hw" in mount option, display MB_HW_X (if available); otherwise, display
only the legacy "MB". This is similar to the cpufreq governor, where only
one governor is allowed to adjust the CPU frequency at a time.

thanks,
Chenyu