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Message-ID: <7ca0bdcc27d4033d04131e2feca5921f85df0ac2.1752167718.git.babu.moger@amd.com>
Date: Thu, 10 Jul 2025 12:16:22 -0500
From: Babu Moger <babu.moger@....com>
To: <corbet@....net>, <tony.luck@...el.com>, <reinette.chatre@...el.com>,
<Dave.Martin@....com>, <james.morse@....com>, <tglx@...utronix.de>,
<mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <akpm@...ux-foundation.org>,
<paulmck@...nel.org>, <rostedt@...dmis.org>, <Neeraj.Upadhyay@....com>,
<david@...hat.com>, <arnd@...db.de>, <fvdl@...gle.com>, <seanjc@...gle.com>,
<thomas.lendacky@....com>, <pawan.kumar.gupta@...ux.intel.com>,
<babu.moger@....com>, <yosry.ahmed@...ux.dev>, <sohil.mehta@...el.com>,
<xin@...or.com>, <kai.huang@...el.com>, <xiaoyao.li@...el.com>,
<peterz@...radead.org>, <me@...aill.net>, <mario.limonciello@....com>,
<xin3.li@...el.com>, <ebiggers@...gle.com>, <ak@...ux.intel.com>,
<chang.seok.bae@...el.com>, <andrew.cooper3@...rix.com>,
<perry.yuan@....com>, <linux-doc@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH v7 08/10] fs/resctrl: Introduce interface to display io_alloc CBMs
The io_alloc feature in resctrl enables system software to configure
the portion of the cache allocated for I/O traffic.
Add "io_alloc_cbm" resctrl file to display CBMs (Capacity Bit Mask) o
fio_alloc feature.
The CBM interface file io_alloc_cbm will reside in the info directory
(e.g., /sys/fs/resctrl/info/L3/). Displaying the resource name is not
necessary. Pass the resource name to show_doms() and print it only if
the name is valid. For io_alloc, pass NULL to suppress printing the
resource name.
When CDP is enabled, io_alloc routes traffic using the highest CLOSID
associated with an L3CODE resource. However, CBMs can be accessed via
either L3CODE or L3DATA resources.
Signed-off-by: Babu Moger <babu.moger@....com>
---
v7: Updated changelog.
Updated use doc (resctrl.rst).
Removed if (io_alloc_closid < 0) check. Not required anymore.
v6: Added "io_alloc_cbm" details in user doc resctrl.rst.
Resource name is not printed in CBM now. Corrected the texts about it
in resctrl.rst.
v5: Resolved conflicts due to recent resctrl FS/ARCH code restructure.
Updated show_doms() to print the resource if only it is valid. Pass NULL while
printing io_alloc CBM.
Changed the code to access the CBMs via either L3CODE or L3DATA resources.
v4: Updated the change log.
Added rdtgroup_mutex before rdt_last_cmd_puts().
Returned -ENODEV when resource type is CDP_DATA.
Kept the resource name while printing the CBM (L3:0=fff) that way
I dont have to change show_doms() just for this feature and it is
consistant across all the schemata display.
v3: Minor changes due to changes in resctrl_arch_get_io_alloc_enabled()
and resctrl_io_alloc_closid_get().
Added the check to verify CDP resource type.
Updated the commit log.
v2: Fixed to display only on L3 resources.
Added the locks while processing.
Rename the displat to io_alloc_cbm (from sdciae_cmd).
---
Documentation/filesystems/resctrl.rst | 18 +++++++++++
fs/resctrl/ctrlmondata.c | 8 +++--
fs/resctrl/internal.h | 2 ++
fs/resctrl/rdtgroup.c | 43 ++++++++++++++++++++++++++-
4 files changed, 67 insertions(+), 4 deletions(-)
diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
index 189c1ccb92d6..c22a9dd667cd 100644
--- a/Documentation/filesystems/resctrl.rst
+++ b/Documentation/filesystems/resctrl.rst
@@ -176,6 +176,24 @@ related to allocation:
When CDP is enabled, io_alloc routes I/O traffic using the highest
CLOSID allocated for the instruction cache (L3CODE).
+"io_alloc_cbm":
+ CBMs(Capacity Bit Masks) that describe the portions of cache instances
+ to which I/O traffic from supported I/O devices are routed.
+
+ 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 DATA and 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 d98e0d2de09f..e78828b0408a 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -381,7 +381,8 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
return ret ?: nbytes;
}
-static void show_doms(struct seq_file *s, struct resctrl_schema *schema, int closid)
+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 {
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 0a1eedba2b03..3d4a3d7696d0 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -374,6 +374,8 @@ void rdt_staged_configs_clear(void);
bool closid_allocated(unsigned int closid);
int resctrl_find_cleanest_closid(void);
+void show_doms(struct seq_file *s, struct resctrl_schema *schema,
+ char *name, int closid);
#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 06c854caa55c..008657e43656 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2004,6 +2004,38 @@ static ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf,
return ret ?: nbytes;
}
+static 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;
+ }
+
+ show_doms(seq, s, NULL, resctrl_io_alloc_closid(r));
+
+out_unlock:
+ mutex_unlock(&rdtgroup_mutex);
+ cpus_read_unlock();
+ return ret;
+}
+
/* rdtgroup information files for one cache resource. */
static struct rftype res_common_files[] = {
{
@@ -2101,6 +2133,12 @@ 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,
@@ -2274,9 +2312,12 @@ 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)
--
2.34.1
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