linux-kernel - Re: [PATCH 10/32] x86/intel_rdt: Adds support to enable Code Data Prioritization

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Date:	Tue, 26 Jul 2016 14:23:51 -0500
From:	Nilay Vaish <nilayvaish@...il.com>
To:	Fenghua Yu <fenghua.yu@...el.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <h.peter.anvin@...el.com>,
	Tony Luck <tony.luck@...el.com>, Tejun Heo <tj@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Stephane Eranian <eranian@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	David Carrillo-Cisneros <davidcc@...gle.com>,
	Ravi V Shankar <ravi.v.shankar@...el.com>,
	Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
	Sai Prakhya <sai.praneeth.prakhya@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>
Subject: Re: [PATCH 10/32] x86/intel_rdt: Adds support to enable Code Data Prioritization

On 12 July 2016 at 20:02, Fenghua Yu <fenghua.yu@...el.com> wrote:
> From: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
>
> On Intel SKUs that support Code Data Prioritization(CDP), intel_rdt
> operates in 2 modes - legacy cache allocation mode/default or CDP mode.
>
> When CDP is enabled, the number of available CLOSids is halved. Hence the
> enabling is done when less than half the number of CLOSids available are
> used. When CDP is enabled each CLOSid maps to a
> data cache mask and an instruction cache mask. The enabling itself is done
> by writing to the IA32_PQOS_CFG MSR and can dynamically be enabled or
> disabled.
>
> CDP is disabled when for each (dcache_cbm,icache_cbm) pair, the
> dcache_cbm = icache_cbm.
>
> Signed-off-by: Vikas Shivappa <vikas.shivappa@...ux.intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/include/asm/intel_rdt.h |  7 +++++
>  arch/x86/kernel/cpu/intel_rdt.c  | 66 ++++++++++++++++++++++++++--------------
>  2 files changed, 51 insertions(+), 22 deletions(-)
>
> diff --git a/arch/x86/include/asm/intel_rdt.h b/arch/x86/include/asm/intel_rdt.h
> index 6e20314..f2cb91d 100644
> --- a/arch/x86/include/asm/intel_rdt.h
> +++ b/arch/x86/include/asm/intel_rdt.h
> @@ -8,6 +8,7 @@
>  #define MAX_CBM_LENGTH                 32
>  #define IA32_L3_CBM_BASE               0xc90
>  #define CBM_FROM_INDEX(x)              (IA32_L3_CBM_BASE + x)
> +#define MSR_IA32_PQOS_CFG              0xc81
>
>  extern struct static_key rdt_enable_key;
>  void __intel_rdt_sched_in(void *dummy);
> @@ -17,6 +18,12 @@ struct clos_cbm_table {
>         unsigned int clos_refcnt;
>  };
>
> +struct clos_config {
> +       unsigned long *closmap;
> +       u32 max_closid;
> +       u32 closids_used;
> +};
> +

I think most of this patch is not about CDP, but about moving from an
independently defined closmap to one defined as part of struct
clos_config.  I suggest we combine part of this patch with patch 03/32
and work with struct clos_config right from the beginning.


Thanks
Nilay