linux-kernel - RE: [PATCH v2 5/7] x86/resctrl: Add interface to enable/disable io

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Message-ID: <SJ1PR11MB6083F03111DBEB3FFD0E8CF3FC142@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Thu, 2 Jan 2025 17:23:27 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: "Chatre, Reinette" <reinette.chatre@...el.com>, Babu Moger
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Subject: RE: [PATCH v2 5/7] x86/resctrl: Add interface to enable/disable
 io_alloc feature

> >> static void rdt_get_sdciae_alloc_cfg(struct rdt_resource *r)
> >>  {
> >>       r->cache.io_alloc_capable = true;
> >> +     resctrl_file_fflags_init("io_alloc",
> >> +                              RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE);
> >>  }
> >
> > I think those fflags will make this file appear in all info cache directories
> > (L2 and L3).
> >
> > Presumably you only want this file (and "io_alloc_cbm" added by next
> > patch) in the L3 directory.
>
> Could you please elaborate why this file should only be in L3 directory? I do not see
> the problem with having it in L2. "io_alloc" communicates to user space if this I/O alloc
> feature is supported and does so with its content as opposed to its existence. For L2
> it will indicate that the feature is not supported.

Good point. I withdraw my comment.

-Tony