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Message-ID: <d7aa590e-7ad5-4eaa-9ea0-94322b802dd5@intel.com>
Date: Fri, 28 Jun 2024 09:54:33 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
<linux-kernel@...r.kernel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, H Peter Anvin
<hpa@...or.com>, Babu Moger <Babu.Moger@....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>,
"Dave Martin" <dave.martin@....com>, Shaopeng Tan
<tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH v3 36/38] fs/resctrl: Add boiler plate for external
resctrl code
Hi James,
On 6/14/24 8:00 AM, James Morse wrote:
> Add Makefile and Kconfig for fs/resctrl. Add ARCH_HAS_CPU_RESCTRL
> for the common parts of the resctrl interface and make X86_CPU_RESCTRL
> depend on this.
>
> Adding an include of asm/resctrl.h to linux/resctrl.h allows some
> of the files to switch over to using this header instead.
>
> Co-developed-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
> Changes since v2:
> * Dropped KERNFS dependency from arch side Kconfig.
> * Added empty trace.h file.
> * Merged asm->linux includes from Dave's patch to decouple those
> patches from this series.
>
> Changes since v1:
> * Rename new file psuedo_lock.c to pseudo_lock.c, to match the name
> of the original file (and to be less surprising).
>
> * [Whitespace only] Under RESCTRL_FS in fs/resctrl/Kconfig, delete
> alignment space in orphaned select ... if (which has nothing to line
> up with any more).
>
> * [Whitespace only] Reflow and re-tab Kconfig additions.
> ---
> MAINTAINERS | 1 +
> arch/Kconfig | 8 +++++
> arch/x86/Kconfig | 5 ++--
> arch/x86/kernel/cpu/resctrl/internal.h | 3 +-
> arch/x86/kernel/cpu/resctrl/monitor.c | 2 +-
> arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 2 +-
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 2 +-
> fs/Kconfig | 1 +
> fs/Makefile | 1 +
> fs/resctrl/Kconfig | 36 +++++++++++++++++++++++
> fs/resctrl/Makefile | 3 ++
> fs/resctrl/ctrlmondata.c | 0
> fs/resctrl/internal.h | 0
> fs/resctrl/monitor.c | 0
> fs/resctrl/pseudo_lock.c | 0
> fs/resctrl/rdtgroup.c | 0
> fs/resctrl/trace.h | 0
> include/linux/resctrl.h | 4 +++
> 18 files changed, 61 insertions(+), 7 deletions(-)
> create mode 100644 fs/resctrl/Kconfig
> create mode 100644 fs/resctrl/Makefile
> create mode 100644 fs/resctrl/ctrlmondata.c
> create mode 100644 fs/resctrl/internal.h
> create mode 100644 fs/resctrl/monitor.c
> create mode 100644 fs/resctrl/pseudo_lock.c
> create mode 100644 fs/resctrl/rdtgroup.c
> create mode 100644 fs/resctrl/trace.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 441b039068d8..64195c298baf 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -18859,6 +18859,7 @@ S: Supported
> F: Documentation/arch/x86/resctrl*
> F: arch/x86/include/asm/resctrl.h
> F: arch/x86/kernel/cpu/resctrl/
> +F: fs/resctrl/
> F: include/linux/resctrl*.h
> F: tools/testing/selftests/resctrl/
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 975dd22a2dbd..4156604dd926 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1431,6 +1431,14 @@ config STRICT_MODULE_RWX
> config ARCH_HAS_PHYS_TO_DMA
> bool
>
> +config ARCH_HAS_CPU_RESCTRL
> + bool
> + help
> + An architecture selects this option to indicate that the necessary
> + hooks are provided to support the common memory system usage
> + monitoring and control interfaces provided by the 'resctrl'
> + filesystem (see RESCTRL_FS).
> +
> config HAVE_ARCH_COMPILER_H
> bool
> help
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 446984277b45..e4dd4097e10f 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -490,8 +490,9 @@ config X86_MPPARSE
> config X86_CPU_RESCTRL
> bool "x86 CPU resource control support"
> depends on X86 && (CPU_SUP_INTEL || CPU_SUP_AMD)
> - select KERNFS
> - select PROC_CPU_RESCTRL if PROC_FS
> + depends on MISC_FILESYSTEMS
> + select ARCH_HAS_CPU_RESCTRL
> + select RESCTRL_FS
> select RESCTRL_FS_PSEUDO_LOCK
> help
> Enable x86 CPU resource control support.
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index bad103f20663..6f6785a31efe 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -7,10 +7,9 @@
> #include <linux/kernfs.h>
> #include <linux/fs_context.h>
> #include <linux/jump_label.h>
> +#include <linux/resctrl.h>
> #include <linux/tick.h>
>
> -#include <asm/resctrl.h>
> -
> #define L3_QOS_CDP_ENABLE 0x01ULL
>
> #define L2_QOS_CDP_ENABLE 0x01ULL
> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
> index 145bd05eafa5..a1539edb25fa 100644
> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
> @@ -17,11 +17,11 @@
>
> #include <linux/cpu.h>
> #include <linux/module.h>
> +#include <linux/resctrl.h>
> #include <linux/sizes.h>
> #include <linux/slab.h>
>
> #include <asm/cpu_device_id.h>
> -#include <asm/resctrl.h>
>
> #include "internal.h"
> #include "trace.h"
> diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> index c096fa106b80..97e901009c91 100644
> --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> @@ -19,12 +19,12 @@
> #include <linux/mman.h>
> #include <linux/perf_event.h>
> #include <linux/pm_qos.h>
> +#include <linux/resctrl.h>
> #include <linux/slab.h>
> #include <linux/uaccess.h>
>
> #include <asm/cacheflush.h>
> #include <asm/cpu_device_id.h>
> -#include <asm/resctrl.h>
> #include <asm/perf_event.h>
>
> #include "../../events/perf_event.h" /* For X86_CONFIG() */
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 969c454b67f1..c7cbd30ac0f2 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -19,6 +19,7 @@
> #include <linux/fs_parser.h>
> #include <linux/sysfs.h>
> #include <linux/kernfs.h>
> +#include <linux/resctrl.h>
> #include <linux/seq_buf.h>
> #include <linux/seq_file.h>
> #include <linux/sched/signal.h>
> @@ -29,7 +30,6 @@
>
> #include <uapi/linux/magic.h>
>
> -#include <asm/resctrl.h>
> #include "internal.h"
>
> DEFINE_STATIC_KEY_FALSE(rdt_enable_key);
> diff --git a/fs/Kconfig b/fs/Kconfig
> index a46b0cbc4d8f..d8a36383b6dc 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -331,6 +331,7 @@ source "fs/omfs/Kconfig"
> source "fs/hpfs/Kconfig"
> source "fs/qnx4/Kconfig"
> source "fs/qnx6/Kconfig"
> +source "fs/resctrl/Kconfig"
> source "fs/romfs/Kconfig"
> source "fs/pstore/Kconfig"
> source "fs/sysv/Kconfig"
> diff --git a/fs/Makefile b/fs/Makefile
> index 6ecc9b0a53f2..da6e2d028722 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -129,3 +129,4 @@ obj-$(CONFIG_EFIVAR_FS) += efivarfs/
> obj-$(CONFIG_EROFS_FS) += erofs/
> obj-$(CONFIG_VBOXSF_FS) += vboxsf/
> obj-$(CONFIG_ZONEFS_FS) += zonefs/
> +obj-$(CONFIG_RESCTRL_FS) += resctrl/
> diff --git a/fs/resctrl/Kconfig b/fs/resctrl/Kconfig
> new file mode 100644
> index 000000000000..a5fbda54d32f
> --- /dev/null
> +++ b/fs/resctrl/Kconfig
> @@ -0,0 +1,36 @@
> +config RESCTRL_FS
> + bool "CPU Resource Control Filesystem (resctrl)"
> + depends on ARCH_HAS_CPU_RESCTRL
> + select KERNFS
> + select PROC_CPU_RESCTRL if PROC_FS
> + help
> + Some architectures provide hardware facilities to group tasks and
> + monitor and control their usage of memory system resources such as
> + caches and memory bandwidth. Examples of such facilities include
> + Intel's Resource Director Technology (Intel(R) RDT) and AMD's
> + Platform Quality of Service (AMD QoS).
> +
> + If your system has the necessary support and you want to be able to
> + assign tasks to groups and manipulate the associated resource
> + monitors and controls from userspace, say Y here to get a mountable
> + 'resctrl' filesystem that lets you do just that.
> +
> + If nothing mounts or prods the 'resctrl' filesystem, resource
> + controls and monitors are left in a quiescent, permissive state.
> +
> + If unsure, it is safe to say N.
> +
Will user ever get opportunity to say "Y" or "N"? It looks to me that
RESCTRL_FS will be "forced" on user as it is selected by the arch specific
config X86_CPU_RESCTRL and be invisble otherwise because of the dependency
on ARCH_HAS_CPU_RESCTRL. The text about when to select "Y" or "N" thus does
not look practical to me and it may be helpful to instead provide
information about when it is selected? I do not know the customs for this
text and if it is intended to document any future usages also.
Reinette
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