From: Babu Moger Date: Thu, 13 Nov 2025 00:57:33 +0000 (-0600) Subject: fs/resctrl: Introduce interface to display io_alloc CBMs X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=77b662326200135fe72cedc47fb1b0e5679d604d;p=thirdparty%2Flinux.git fs/resctrl: Introduce interface to display io_alloc CBMs Introduce the "io_alloc_cbm" resctrl file to display the capacity bitmasks (CBMs) that represent the portions of each cache instance allocated for I/O traffic on a cache resource that supports the "io_alloc" feature. io_alloc_cbm resides in the info directory of a cache resource, for example, /sys/fs/resctrl/info/L3/. Since the resource name is part of the path, it is not necessary to display the resource name as done in the schemata file. When CDP is enabled, io_alloc routes traffic using the highest CLOSID associated with the CDP_CODE resource and that CLOSID becomes unusable for the CDP_DATA resource. The highest CLOSID of CDP_CODE and CDP_DATA resources will be kept in sync to ensure consistent user interface. In preparation for this, access the CBMs for I/O traffic through highest CLOSID of either CDP_CODE or CDP_DATA resource. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/55a3ff66a70e7ce8239f022e62b334e9d64af604.1762995456.git.babu.moger@amd.com --- diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst index 91c71e254bbd7..e7994538e0cef 100644 --- a/Documentation/filesystems/resctrl.rst +++ b/Documentation/filesystems/resctrl.rst @@ -182,6 +182,25 @@ related to allocation: available for general (CPU) cache allocation for both the CDP_CODE and CDP_DATA resources. +"io_alloc_cbm": + Capacity bitmasks that describe the portions of cache instances to + which I/O traffic from supported I/O devices are routed when "io_alloc" + is enabled. + + CBMs are displayed in the following format: + + =;=;... + + Example:: + + # cat /sys/fs/resctrl/info/L3/io_alloc_cbm + 0=ffff;1=ffff + + When CDP is enabled "io_alloc_cbm" associated with the CDP_DATA and CDP_CODE + resources may reflect the same values. For example, values read from and + written to /sys/fs/resctrl/info/L3DATA/io_alloc_cbm may be reflected by + /sys/fs/resctrl/info/L3CODE/io_alloc_cbm and vice versa. + Memory bandwidth(MB) subdirectory contains the following files with respect to allocation: diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c index 454fdf3b9f3c4..1ac89b107e6f1 100644 --- a/fs/resctrl/ctrlmondata.c +++ b/fs/resctrl/ctrlmondata.c @@ -381,7 +381,8 @@ out: return ret ?: nbytes; } -static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid) +static void show_doms(struct seq_file *s, struct resctrl_schema *schema, + char *resource_name, int closid) { struct rdt_resource *r = schema->res; struct rdt_ctrl_domain *dom; @@ -391,7 +392,8 @@ static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int clo /* Walking r->domains, ensure it can't race with cpuhp */ lockdep_assert_cpus_held(); - seq_printf(s, "%*s:", max_name_width, schema->name); + if (resource_name) + seq_printf(s, "%*s:", max_name_width, resource_name); list_for_each_entry(dom, &r->ctrl_domains, hdr.list) { if (sep) seq_puts(s, ";"); @@ -437,7 +439,7 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of, closid = rdtgrp->closid; list_for_each_entry(schema, &resctrl_schema_all, list) { if (closid < schema->num_closid) - show_doms(s, schema, closid); + show_doms(s, schema, schema->name, closid); } } } else { @@ -823,3 +825,40 @@ out_unlock: return ret ?: nbytes; } + +int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq, void *v) +{ + struct resctrl_schema *s = rdt_kn_parent_priv(of->kn); + struct rdt_resource *r = s->res; + int ret = 0; + + cpus_read_lock(); + mutex_lock(&rdtgroup_mutex); + + rdt_last_cmd_clear(); + + if (!r->cache.io_alloc_capable) { + rdt_last_cmd_printf("io_alloc is not supported on %s\n", s->name); + ret = -ENODEV; + goto out_unlock; + } + + if (!resctrl_arch_get_io_alloc_enabled(r)) { + rdt_last_cmd_printf("io_alloc is not enabled on %s\n", s->name); + ret = -EINVAL; + goto out_unlock; + } + + /* + * When CDP is enabled, the CBMs of the highest CLOSID of CDP_CODE and + * CDP_DATA are kept in sync. As a result, the io_alloc CBMs shown for + * either CDP resource are identical and accurately represent the CBMs + * used for I/O. + */ + show_doms(seq, s, NULL, resctrl_io_alloc_closid(r)); + +out_unlock: + mutex_unlock(&rdtgroup_mutex); + cpus_read_unlock(); + return ret; +} diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h index 145e22f9a3504..779a575e08282 100644 --- a/fs/resctrl/internal.h +++ b/fs/resctrl/internal.h @@ -438,6 +438,8 @@ ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off); const char *rdtgroup_name_by_closid(u32 closid); +int resctrl_io_alloc_cbm_show(struct kernfs_open_file *of, struct seq_file *seq, + void *v); #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp); diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c index 9f9bd31e96625..ac326db9b5ba0 100644 --- a/fs/resctrl/rdtgroup.c +++ b/fs/resctrl/rdtgroup.c @@ -1971,6 +1971,12 @@ static struct rftype res_common_files[] = { .seq_show = resctrl_io_alloc_show, .write = resctrl_io_alloc_write, }, + { + .name = "io_alloc_cbm", + .mode = 0444, + .kf_ops = &rdtgroup_kf_single_ops, + .seq_show = resctrl_io_alloc_cbm_show, + }, { .name = "max_threshold_occupancy", .mode = 0644, @@ -2171,9 +2177,12 @@ static void io_alloc_init(void) { struct rdt_resource *r = resctrl_arch_get_resource(RDT_RESOURCE_L3); - if (r->cache.io_alloc_capable) + if (r->cache.io_alloc_capable) { resctrl_file_fflags_init("io_alloc", RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE); + resctrl_file_fflags_init("io_alloc_cbm", + RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE); + } } void resctrl_file_fflags_init(const char *config, unsigned long fflags)