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 <babu.moger@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
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 91c71e254bbd76aa27a2b7832b8f97bf8c7f73b7..e7994538e0cef74e33123c296adeef369a288ae6 100644 (file)
--- 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:
+
+                       <cache_id0>=<cbm>;<cache_id1>=<cbm>;...
+
+               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 454fdf3b9f3c4989f5e33ade2ff3c653f5b350f4..1ac89b107e6f12cf2a7e8e3e13293b916490b030 100644 (file)
--- 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 145e22f9a3504b27c1adfa2698d5438a1263c89e..779a575e08282c283ed0b20784558bf37c994cce 100644 (file)
--- 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 9f9bd31e966257845b0fb8ddf8f9da803884c727..ac326db9b5ba09924d8453dc42f3be92ca76dca2 100644 (file)
--- 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)