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Date: Tue, 15 Jun 2021 12:51:55 -0500
From: Babu Moger <babu.moger@....com>
To: James Morse <james.morse@....com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Cc: Fenghua Yu <fenghua.yu@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
H Peter Anvin <hpa@...or.com>,
shameerali.kolothum.thodi@...wei.com,
Jamie Iles <jamie@...iainc.com>,
D Scott Phillips OS <scott@...amperecomputing.com>,
lcherian@...vell.com
Subject: Re: [PATCH v4 03/24] x86/resctrl: Add a separate schema list for
resctrl
On 6/14/21 3:09 PM, James Morse wrote:
> Resctrl exposes schemata to user-space, which allow the control values
> to be specified for a group of tasks.
>
> User-visible properties of the interface, (such as the schemata names
> and how the values are parsed) are rooted in a struct provided by the
> architecture code. (struct rdt_hw_resource). Once a second architecture
> uses resctrl, this would allow user-visible properties to diverge
> between architectures.
>
> These properties should come from the resctrl code that will be common
> to all architectures. Resctrl has no per-schema structure, only struct
> rdt_{hw_,}resource. Create a struct resctrl_schema to hold the
> rdt_resource. Before a second architecture can be supported, this
> structure will also need to hold the schema name visible to user-space
> and the type of configuration values for resctrl.
>
> Reviewed-by: Jamie Iles <jamie@...iainc.com>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Changes since v3:
> * Fixed a spelling mistake, removed a space.
>
> Changes since v2:
> * Expanded comments.
> * Shuffled commit message,
>
> Changes since v1:
> * Renamed resctrl_all_schema list
> * Used schemata_list as a prefix to make these easier to search for
> * Added kerneldoc string
> * Removed 'pending configuration' reference in commit message
> ---
> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 43 +++++++++++++++++++++++++-
> include/linux/resctrl.h | 11 +++++++
> 3 files changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
> index 235cf621c878..f6790d03f056 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -106,6 +106,7 @@ extern unsigned int resctrl_cqm_threshold;
> extern bool rdt_alloc_capable;
> extern bool rdt_mon_capable;
> extern unsigned int rdt_mon_features;
> +extern struct list_head resctrl_schema_all;
>
> enum rdt_group_type {
> RDTCTRL_GROUP = 0,
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 9a8665c8ab89..14ea1212f476 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -39,6 +39,9 @@ static struct kernfs_root *rdt_root;
> struct rdtgroup rdtgroup_default;
> LIST_HEAD(rdt_all_groups);
>
> +/* list of entries for the schemata file */
> +LIST_HEAD(resctrl_schema_all);
> +
> /* Kernel fs node for "info" directory under root */
> static struct kernfs_node *kn_info;
>
> @@ -2109,6 +2112,35 @@ static int rdt_enable_ctx(struct rdt_fs_context *ctx)
> return ret;
> }
>
> +static int schemata_list_create(void)
> +{
> + struct resctrl_schema *s;
> + struct rdt_resource *r;
> +
> + for_each_alloc_enabled_rdt_resource(r) {
> + s = kzalloc(sizeof(*s), GFP_KERNEL);
> + if (!s)
> + return -ENOMEM;
> +
> + s->res = r;
> +
> + INIT_LIST_HEAD(&s->list);
> + list_add(&s->list, &resctrl_schema_all);
> + }
> +
> + return 0;
> +}
> +
> +static void schemata_list_destroy(void)
> +{
> + struct resctrl_schema *s, *tmp;
> +
> + list_for_each_entry_safe(s, tmp, &resctrl_schema_all, list) {
> + list_del(&s->list);
> + kfree(s);
> + }
> +}
> +
> static int rdt_get_tree(struct fs_context *fc)
> {
> struct rdt_fs_context *ctx = rdt_fc2context(fc);
> @@ -2130,11 +2162,17 @@ static int rdt_get_tree(struct fs_context *fc)
> if (ret < 0)
> goto out_cdp;
>
> + ret = schemata_list_create();
> + if (ret) {
> + schemata_list_destroy();
> + goto out_mba;
> + }
> +
> closid_init();
>
> ret = rdtgroup_create_info_dir(rdtgroup_default.kn);
> if (ret < 0)
> - goto out_mba;
> + goto out_schemata_free;
>
> if (rdt_mon_capable) {
> ret = mongroup_create_dir(rdtgroup_default.kn,
> @@ -2184,6 +2222,8 @@ static int rdt_get_tree(struct fs_context *fc)
> kernfs_remove(kn_mongrp);
> out_info:
> kernfs_remove(kn_info);
> +out_schemata_free:
> + schemata_list_destroy();
> out_mba:
> if (ctx->enable_mba_mbps)
> set_mba_sc(false);
> @@ -2425,6 +2465,7 @@ static void rdt_kill_sb(struct super_block *sb)
> rmdir_all_sub();
> rdt_pseudo_lock_release();
> rdtgroup_default.mode = RDT_MODE_SHAREABLE;
> + schemata_list_destroy();
> static_branch_disable_cpuslocked(&rdt_alloc_enable_key);
> static_branch_disable_cpuslocked(&rdt_mon_enable_key);
> static_branch_disable_cpuslocked(&rdt_enable_key);
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index be6f5df78e31..425e7913dc8d 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -154,4 +154,15 @@ struct rdt_resource {
>
> };
>
> +/**
> + * struct resctrl_schema - configuration abilities of a resource presented to
> + * user-space
> + * @list: Member of resctrl_schema_all.
> + * @res: The resource structure exported by the architecture to describe
> + * the hardware that is configured by this schema.
> + */
> +struct resctrl_schema {
> + struct list_head list;
> + struct rdt_resource *res;
It will be better to be consistent with the naming.
struct rdt_resource *resctrl;
> +};
> #endif /* _RESCTRL_H */
>
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